PURE  MILK 


AND  THK 


PUBLIC  HEALTH 


A    MANTAL,  OF 


Milk  and  Dairy  Inspection 


BY  ARCHIBALD  ROBINSON  WARD,  B.  S.  A.,  D.  V.  M 

Assistant  Professor  of  Bacteriology  and  Director  of  the  State  Hygienic  laboratory, 
University  of  California,  Berkeley,  California. 


WITH  TWO  CHAPTKRS 


BY  MYER  EDWARD  JAFFA,  M.S. 

Professor  of  Nutrition  and  Director  of  the  State  Food  and  Drnn  I,aboraton 
University  of  California. 


WITH  SEVENTEEN  ILLUSTRATIONS 


ITHACA,  N.  V 

TAYLOR  &  CAKPKNTKK 

1909 


COPYRIGHT  1909 
BY  TAYLOR  ^  CARPKXTKR 


TO 

VERANUS  ALVA  MOORE 

WHOSE  INSPIRING  WORK  AS  A  TEACHER 
AND  INVESTIGATOR  IN  THE  FIELD  OF  COM- 
PARATIVE PATHOLOGY  AND  BACTERIOLOGY 
IS  EXERTING  A  PROFOUND  INFLUENCE  IN 
UPLIFTING  THE  VETERINARY  PROFESSION, 
THIS  BOOK  IS  DEDICATED. 


190867 


PREFACE. 


The  relation  of  milk  to  the  public  health  and  the  means 
employed  to  ensure  a  safe  milk  supply  is  a  subject  of  varied 
aspects.  The  proper  control  of  the  public  milk  supply  requires 
more  or  less  of  the  services  of  the  bacteriologist,  the  chemist, 
the  physician,  the  veterinarian,  and  the  progressive  dairyman. 
The  ordinary  fund  of  technical  knowledge  possessed  by  any  one 
of  these  classes  is  not  sufficient  for  coping  with  the  difficulties 
encountered  in  carrying  on  efficient  and  comprehensive  meas- 
ures for  milk  and'  dairy  inspection.  Furthermore,  knowledge 
concerning  the  subject  is  being  rapidly  increased  by  contribu- 
tions widely  scattered  in  technical  journals. 

The  writer  has  attempted  the  difficult  task  of  assembling  the 
essential  facts  for  the  information  of  the  health  officer  and 
others  directly  concerned  in  the  crusade  for  better  milk.  The 
class  of  individuals  particularly  addressed  is  such,  that  a  gen- 
eral knowledge  of  bacteriology  is  assumed  to  be  possessed  by 
the  reader. 

Each  chapter  is  accompanied  by  a  list  of  references  bearing 
on  the  subjects  discussed.  Throughout  the  text,  numbers  in 
parenthesis,  referring  to  the  authorities  given  at  the -end  of  the 
chapter,  have  been  freely  used.  These  references  serve  in  some 
cases  to  give  statements  greater  weight  than  a  mere  unsup- 
ported personal  opinion  would  have,  and  in  all  cases  permit 
those  particularly  interested  to  gain  access  readily  to  the  details 
concerning  the  points  at  issue. 

In  the  preparation  of  the  book,  the  writer  has  become  greatly 
obligated  to  his  colleague,  Professor  M.  E.  Jaffa,  for  writing 
chapters  X  and  XI.  With  reference  to  those  chapters,  Pro- 
fessor Jaffa  desires  to  have  it  stated  that  he  has  not  attempted 
to  present  the  details  of  the  more  common  methods  employed 
in  the  chemical  examination  of  milk.  This  branch  of  milk 
inspection  is  the  most  advanced  and  the  methods  are  well  estab- 
lished. He  has  been  content  to  indicate  what  should  be  done 


VI  PREFACE. 

and  to  refer  to  standard  works  on  the  subject  for  the  methods 
except  in  the  case  of  some  of  the  simple  tests. 

Dr.  William  H.  Boynton,  Assistant  in  Pathology  and  Bac- 
teriology, New  York  State  Veterinary  College,  has  very  gener- 
ously permitted  the  use  of  the  photographs  appearing  as  figures 
13  and  14,  together  with  his  description  of  them,  in  advance 
of  publication  by  himself.  Professor  G.  C.  Watson,  General 
Manager  of  the  Tully  Farms,  Tully,  N.  Y.,  has  kindly  per- 
mitted the  use  of  photographs  appearing  as  figures  3  and  4. 
Dr.  Francis  H.  Slack,  Chairman  of  the  Committee  of  the 
American  Public  Health  Association  on  Standard  Methods  of 
Bacterial  Milk  Analysis,  has  rendered  assistance  by  furnishing 
a  manuscript  copy  of  the  1908  report  of  that  Committee. 
Specific  acknowledgement  as  to  sources  of  information  has 
been  made  largely  throughout  the  text  by  means  of  the  system 
of  references  employed. 

It  is  not  safe  to  indulge  in  the  hope  that  important  work 
has  not  been  overlooked,  or  that  new  facts  may  not  require  a 
modification  of  attitude  towards  certain  troublesome  problems. 
Therefore,  assistance  tending  to  improve  the  book  will  be 
gratefully  received. 

A.  R.  W. 


TABLE  OF  CONTENTS. 


LIST  OF  FIOURKS  ix  TKXT  xiu 

CHAPTER  I. 

THK  CONTAMINATION  OF  MII^K. 


Character  of  bacteria 
Significance 
Foremilk 
Coat  of  animal 

Hxterior  of  udder  6 

^Shape  of  milk  pail  7 

«/fhe  milker 

Milking  machines 

V  Stable  -,    10 

Floor  10 

Mangers  and  stanchions 
Barn  improvements 
Feeding 

vBpecial  milking  rooms 

^Cleansing  of  utensils.  13 

Scalding   ..  13 

Construction  of  utensils  15 

^Handling  milk. 

Bottling  milk....  I6 

Milk  room  ....  16 

/Delivery  of  milk..  16 

Milk  flavors 

Sediments  17 

References 

CHAPTER  II. 

CHANGES  IN  MII.K  CAUSED  BY  BACTERIA. 

Significance  of  bacterial  contamination  ... 

Numbers  of  bacteria  in  market  milk  .... 
Kffect  of  temperature  on  bacterial  growth.. 
vMethods'of  cooling 
vMilk  during  transportation. 
Preservation  bv  chemicals  .....  26 


VIII  CONTEXTS. 

Lactic  acid  fermentation  26 

Putrefactive  processes 29 

Organisms  causing  putrefaction ....  29 

Antagonism  of  lactic  acid  fermentation  29 

Conditions  controlling  putrefaction  29 

Source  of  putrefactive  organisms  30 

Toxic  milk  ...  30 

Ropy  milk  ...  30 

Cause  of  ropy  milk  31 

Biological  characteristics  of  //.  I  act  is  I'isrostts....  32 

Sources  of  contamination  of  milk  32 

Means  of  combating  ropy  milk  ......  33 

Germicidal  activity  34 

References    ...  .  38 

CHAPTKR  III. 

EPIDEMIC  DISKASKS  TRANSMITTED  BY  MIIyK. 

Transmission  of  diseases  of  man  bv  milk  41 

Character  of  milk-borne  epidemics  41 

Typhoid  fever  42 

Investigations  in  the  District  of  Columbia..  42 

Importance  of  milk  as  a  carrier  43 

Sources  of  the  contamination  of  milk  45 

Detection  of  milk-borne  typhoid  fever  epidemics  46 

Berkeley,  Cal.,  outbreak  49 

Diphtheria  .    51 

Recognition  of  milk-borne  diphtheria  epidemics  52 

Milk-borne  diphtheria  in  Oroville,  Cal.  53 

Scarlet  fever 54 

Gastro-intestiiial  infections  55 

References  .  56 

CHAPTKR  IV. 

BOYINK  TrBERCn.OSIS  AND  OTHER  CATTLE  DISEASES. 

Bovine  tuberculosis          59 

Losses  to  the  live  stock  industry  59 

Transmission  by  milk  59 

Infection  of  swine  60 

Insidious  onset  60 

Conditions  governing  prevalence  60 

Prevalence  in  herds 61 

Contamination  of  milk  by  tubercle  bacilli  ..  62 

Tubercle  bacilli  in  market  milk  bt 

Human  and  bovine  tvpes  of  tubercle  bacilli ...  63 


•     CONTENTS.  IX 

Views  of  Koch  64 

Bovine  tubercle  bacilli  in  man..  .  64 

Intermediate  types  of  tubercle  bacilli  65 

Channels  of  infection  65 

International  Congress  of  1908  66 

Tuberculosis  in  Japan  66 

Present  status  of  controversy  67 

Protection  of  the  milk  supply  67 

Measures  against  bovine  tuberculosis  67 

Physical  examination 
Tuberculin  test 
New  tests  for  tuberculosis 
Stable  sanitation  and  tuberculosis  72 

Tuberculin  test  ordinances  ...  72 

Clean  herds  the  goal  . 
The  Washington  plan 
Test  by  city  official 

Test  by  any  licensed  veterinarian  76 

Milk  contracts  76 

Application  of  the  tuberculin  test  77 

Temporary  numbers 

Facilitating  observations  of  temperatures  77 

Injection  with  tuberculin  79 

Temperatures  after  injection 
Interpretation  of  temperatures 

Limitations  of  tuberculin  test  79 

Fraud 

Permanent  identification  of  animals 
Disposal  of  tubercular  animals 
Disinfection 

Education  of  dairymen  concerning  bovine  tuberculosis 

Anthrax  l% 

Suppuration 

Cowpox 

Parturition  disturbances .... 

Malta  fever  87 

Foot  and  mouth  disease 

Milk-sickness 

References 

CHAPTER  V. 

MUNICIPAL,  SANITARY  CONTROL  OF  MII.K. 

Control  of  milk  supply 
•^Inspection 

The  dairv  score  card  . 


X  CONTENTS. 

Improvement  in  Richmond.  Ya.  103 

Washington  milk  supply  104 

Educational  activities  104 

Inspection  of  cows  105 

Inspection  of  dairy  apparatus  105 

Inspection  of  water  supply  106 

Scope  of  inspection  106 

The  score  card  for  city  milk  plants  106 

Milk-borne  epidemics  109 

Temperature  standard  109 

Numerical  determinations  of  bacteria  in  milk  110 

Education  of  the  public  112 

References  112 

CHAPTER  VI. 

PASTEURIZATION  OK  MILK. 

General  definition  114 

Incentives  for  pasteurization  114 

^Conditions  required  for  killing  bacteria  115 

Bacterium  tuberculosis  115 

Alteration  of  milk  by  heat  115 

Cooked  taste  115 

Alterations  of  milk  constituents  115 

Creaming  quality  116 

Vital  qualities  of  milk  116 

Spore-bearing    bacteria.  116 

Bactericidal   efficiency  117 

Low-temperature  pasteurization.  117 

High-temperature  pasteurization  118 

Commercial  pasteurization  .    118 

Efficiency  119 

Continuous-flow  machines  popular  120 

Care  subsequent  to  heating  121 

*» Pasteurization  in  Chicago 121 

Pasteurized  milk  in  infant  feeding 122 

^-Pasteurization  of  municipal  milk  supplies 123 

References     .    124 

CHAPTER  VII. 

MICROSCOPIC  TESTS  OK  MII,K. 

Mammitis  in  the  cow 126 

Tests  for  cellular  content  of  milk  126 

Stokes'  test  126 

Stewart's  test  ...  ..  127 


CONTENTS.  XI 

Slack's  test 

Doane- Buckley  test 

Savage's  test  ..:  131 

Troniinsdorff's  test  131 

Significance  of  results  132 

Streptococci  in  milk 

Microccocci  in   milk 

Leucocytes  in  milk  134 

Summary  136 

Bloody   milk 
References 

CHAPTER  VIII. 

IJACTKRIO^OGICAI,  KXAMINATION  OF   MII,K. 

Numerical  determination  of  bacteria 

Significance  of  results 

Microscopic  estimate  of  bacteria 

Tests  for  ]>.  toll 

Kxaminations  for  typhoid  fever  and  diphtheria  bacilli 

Tubercle  bacilli  ' 

Determination  of  streptococci 

Qualitative  determinations 

References  ... 

CHAPTER  IX. 

CKRTIFIKD  MII.K 

Milk  commissions .... 

Association  of  milk  commissions 

Source   of  authority 

Field  of  milk  commission    activities 
Agreement  with  dairymen 

Sanitary  requirements  for  dairymen 
Experts  employed  by  milk  commissions 

Veterinary   inspection 

Bacteriological  examinations  165 

Chemical  examinations.  166 

Medical  inspection.. 
V-The  certified  milk  package 

Amount  of  certified  milk  produced.  168 

Fraudulent  certified  milk 
I  Maintenance  of  standard 
Milk  dispensaries 

Rochester,  N.  Y.,  milk   dispensaries 

References  172 


XII  CONTENTS. 

CHAPTKR  X. 

TH1-;   ANALYSIS  OK  MII.K. 

Introduction  174 

Composition  of  milk  174 

Protein  174 

Fat  174 

Carbohydrates  1 76 

Mineral  matter  176 

Solids  of  milk  176 

Effect  of  feeding  on  the    composition  of  milk  176 

Sampling  milk  177 

Specific  gravity  177 

Determination  of  fat  in  milk  and  cream  179 

Interpretation  of  specific  gravity  and  fat  180 

Solids  not  fat  ISO 

Preliminary  tests  of  milk  182 

Acidity  of  milk  182 

Federal  standards  183 

State   standards  1S4 

Collection  of  samples  1<S4 

References  185 

CHAPTKR  XI. 

AIH-I/TKRATION  OK  MILK. 

Introduction  187 

Tests  for  preservatives  190 

Borax  190 

Formaldehyde  190 

Hehner's  test  for  formaldehyde  191 

Leach's  test  for  formaldehyde  191 

Watering  of  milk  191 

Skimming 192 

Carbonate  of  soda 192 

Thickening  agents  for  cream  193 

Heated  milk  193 

Coloring  matter  193 

References  194 


FIGURES  IX  TEXT. 

Fig.     1.     Section  of  one  quarter  of  the  udder  of  a  co\v  1 

Fig.     2.      Pearson's  milk  pail  7 

Fig.     3.     A  convenient  stable  10 


[LXrUSTRATIONS. 


XIII 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 

Fig.    12. 

Fig.  13. 
Fig.  14. 

Fig.  15. 
Fig.  16. 

Fig.  17. 


Sterili/.er  containing  racks  for  holding  bottles  14 
Ropy  cream  lifted  with  a  fork  31 
liacillns  lactis  VtSfQSUS  31 
Germicidal  action  of  freshly  drawn  milk  35 
L,aundrv  in  which  milk  cans  were  washed  50 
Conditions  surrounding-  a  case  of  typhoid  fever  51 
Blank  for  recording  temperatures  78 
Ear-tag  for  marking  cattle  SO 
Card  employed  by  the  writer  for  the  identification  of  cows  81 
Moak's  card  for  identifying  cows  83 
Diagram  showing 'improvement  in  dairy  scores  in  Rich- 
mond, Va.  104 
Section  of  udder  showing  epithelial  cells  ..  134 
vSection  of  udder  showing  epithelial  cells  and  polynuclear 

leucocytes                                                                                     -  135 
Chart  showing  relation  of  municipal  milk  stations  to  infant 

mortality  171 


Appendix  A. 
Appendix  B. 
Appendix  C. 
Appendix  D. 
Appendix  E. 


APPENDICEvS. 

Dairy  ordinance  of  Berkeley,  Cal. 

Chicago  tuberculin  test  ordinance 

Duluth  milk  ordinance 

Blank  for  reporting  existence  of  infectious  diseases.. 

Poster  for  dairy  barns 


195 
200 
206 
211 
212 


Index 


214 


CHAPTER  I. 


THE  CONTAMINATION  OF  MILK. 


Uddef.  Milk  conies  in  contact  with  bacteria  in  the  lactif- 
erous ducts  of  the  udder  at  the  moment  of  secretion.  The 
normal  healthy  udder  of  the  cow  harbors  bacteria  throughout 
its  whole  extent.  Fig.  1 
shows  the  extent  of  the 
lactiferous  ducts  of  the 
udder  and  the  direct  com- 
munication with  the  ori- 
fice of  the  teat. 

There  was  current  at 
one  time  a  belief  that  the 
interior  of  the  udder  is 
sterile,  except,  perhaps, 
the  teats,  and  that  failure 
to  obtain  sterile  samples 
of  milk  was  due  to  con- 
tamination from  bacteria 
in  the  teats,  or  from  ex- 
ternal sources.  Moore 
(41)  suggested  the 
method  of  attacking  the 
problem  by  the  bacterio- 
logical examination  of 
the  normal  udders  of  re- 
cently slaughtered  cows. 
The  results  obtained  by 
this  method  of  investi- 
gation (42,  44,  66,  67) 
diametrically  opposed  Fig-  1-  Section  of  one  quarter  of  the 

current  belief  and  have    udder  of  a  cow  at  a  plane  intersectinS 
Iave     the  teat  and  milk  cistern.     Photograph 

led  numerous  workers  to     by  the  author,  from  a  museum  specimen 
repeat     the    experiment    prepared  by  Dr.  G.  S.  Hopkins. 


2  THE  CONTAMINATION  OF  MILK. 

(5,  25,  27,  28,  47).  The  conclusions  drawn  from  this  line  of 
work  have  been  in  substantial  agreement  upon  the  point  that 
milk  is  contaminated  before  it  reaches  the  teats.  The  subject 
is  further  treated  in  references  4,  9,  26,  31,  32,  68. 

The  number  of  bacteria  found  in  the  udder  is  less  than 
would  be  expected  elsewhere  under  similar  conditions  of  food, 
moisture  and  temperature  away  from  vital  influences.  The 
germicidal  influence  of  fresh  milk  has  been  cited  as  an  explan- 
ation of  the  fact  (25,  28).  The  last  of  the  milk  drawn  at 
any  one  milking  contains  less  bacteria  than  that  first  drawn, 
but  is  seldom  found  to  be  sterile,  if  any  but  minute  quantities 
are  taken  for  examination.  In  fact,  the  "  strappings  "  have 
been  found  to  contain  more  bacteria  per  cc.  than  that  drawn 
immediately  before  stripping.  If  a  cow  is  not  stripped, — that 
is,  if  a  little  milk  is  left  in  the  udder, — the  next  milking  will 
show  a  number  of  bacteria  larger  than  usual.  This  fact  has 
been  explained  by  assuming  that  thorough  milking  removes 
the  bacteria  from  the  milk  ducts  more  completely  than  the 
ordinary  milking  (60).  It  is  evident  that  the  few  bacteria 
remaining  in  the  ducts  after  milking  constitute  the  source  of 
the  relatively  larger  numbers  in  the  milk  obtained  during  the 
fore  and  middle  portions  of  the  succeeding  milking.  It  is  not 
believed  that  the  udder  is  subject  to  indiscriminate  invasion  by 
a  variety  of  forms,  but  rather  that  the  conditions  found  there 
are  such  as  limit  the  bacterial  flora.  A  number  of  attempts  to 
colonize  the  udder  \vith  a  variety  of  organisms  have  not  met 
with  success.  Bacillus  prodigiosus ,  an  organism  easily  recog- 
nized in  cultures  by  the  red  color,  has  been  used  several  times 
with  the  result  that  inflammatory  conditions  have  been  set  up. 
The  observed  persistence  of  this  organism  for  twenty-two  days, 
while  the  udder  was  inflamed,  does  not  prove  .much,  in  view 
of  the  disease,  and  it  was  obtained  in  constantly  decreasing 
numbers,  which  led  to  the  conclusion  that  multiplication  had 
not  occurred  (53).  In  one  instance  the  teat  of  a  goat  was 
injected  with  B.  prodigiosus  and  after  slaughter,  three  days 
later,  cultures  showed  that  the  organisms  had  invaded  the 
udder  (25).  The  fact  that  this  particular  organism  is  not 
an  udder  organism,  and  was  used  on  account  of  its  chromo- 


UDDER.  3 

genie  power,  should  be  noted.  Experiments  with  forms 
undoubtedly  habituated  to  conditions  within  the  udder  have 
been  made  in  very  few  instances  and  further  work  along  this 
line  is  desirable.  The  observed  persistence  of  certain  bacteria 
in  certain  particular  quarters  of  the  cow's  udder  from  day  to 
day  is  of  significance  (26,  66).  The  presence  of  bacteria  in 
the  udder  is  paralleled  by  the  case  of  other  mucous  membranes. 
These  facts  render  it  unnecessary  to  look  to  hematogenous 
infection  as  the  immediate  source  of  the  bacteria  in  the  milk, 
even  though  bacteria  have  been  demonstrated  in  other  normal 
organs  like :  the  spleen  (21).  Such  an  explanation  of  the 
source  of  the  bacteria  would  hardly  account  for  the  difference 
of  the  bacterial  flora  of  different  quarters  of  the  udder.  No 
evidence  has  been  brought  forward  to  substantiate  the  notion 
that  the  bacterial  content  of  milk  is  influenced  by  bacteria  in 
feed  or  water  transferred  via  intestines,  blood,  and  udder. 
Conclusions  contradicting  this  view  have  been  drawn  from 
observations  which  have  shown  that  the  common  bacterial  flora 
of  the  udder  is  quite  different  from  that  of  the  intestines  (26). 
Experiments  have  been  made  by  feeding  certain  micro-organ- 
isms to  cows  and  then  searching  for  the  same  organisms  in  the 
milk,  without  success.  The  results  might  have  been  otherwise 
if  care  had  not  been  taken  to  prevent  contamination  from  the 
feees.  One  writer  used  B '.  prodigiosus  (66),  while  another  (26) 
used  the  same  organism  in  one  trial,  and  at  another  time  used 
distillers'  grains  containing  yeasts,  oidium,  proteuS,  bacilli., 
and  streptococci.  The  bacterial  content  of  milk  drawn  under 
aseptic  precautions  has  been  determined  in  .cows  fed  on  hay 
and  on  grass,  and  no  difference  was  found  in  the  numbers 
present  in  the  milk  (26) .  The'  bacteria  in  feed  and  water  may 
modify  the  bacterial  co'ntent  of  the  milk,  but  by  other  channels 
than  through  the  interior  of  the  udder. 

Character  of  bacteria.  The  Organisms  most  frequently  found 
are  micrococci,  in  general  capable  of  producing  visible  changes 
in  milk  rather  tardily  (67),  and  hence  they  do  not  interfere  with 
its  apparent  keeping  quality.  Conn,  Esten  and  Stocking  (ll) 
have  pointed  out  that  one  of  these  udder  organisms  {Micro- 
coccus  lactis  varians}  is  the  most  common  and  widely  distributed 


4  THE  CONTAMINATION  OF  MILK. 

organism  in  milk,  and  have  observed  that  it  is  identical  with, 
or  closely  allied  to,  Micrococcus  pyogenes  aureus  {staphylococcus 
pyogenes  aiireus} .  Willem  and  Minne  likewise  regard  these 
organisms,  found  in  freshly  drawn  milk,  as  M.  pyogenes  (68). 
Streptococci,  indistinguishable  from  Streptococcus  pyogenes, 
have  been  isolated  from  milk  taken  from  the  normal  udder 
under  aseptic  precautions  (47).  They  have  been  observed  in 
the  milk  of  a  cow  in  the  Cornell  University  dairy  herd  for  a 
period  of  two  years  and  a  half,  during  which  time  there  was 
no  occurrenc^ <)f  udder  trouble.  This  streptococcus  when 
injected  int6  a  healthy  udder  produced  mammitis.  The  ex- 
cellent record  of  milk  production  for  several  years  previous 
gave  assurance  that  the  animal  had  not  suffered  a  severe  attack 
of  streptococcus  infection  of  the  udder  (47).  A  number  of 
species  have  been  described  as  occurring  in  freshly  drawn  milk, 
but  the  variety  of  species  is  very  much  restricted  as  compared 
with  those  encountered  in  market  milk. 

Significance.  The  presence  of  bacteria  within  the  udder  con- 
stitutes an  obstacle  to  the  production  of  absolutely  sterile  milk. 
v.  Freudenreich  collected  samples,  with  aseptic  precautions,  at 
the  beginning,  the  middle  and  the  end  of  the  milking,  deter- 
mining the  number  of  bacteria  present.  The  average  results  of 
185  determinations  gave  for  the  beginning,  6505  per  cc.;  for 
the  middle,  1341  percc.;  and  for  the  end,  769  percc.  Kuntze 
(Ref.  .22,  Chap.  II)  obtained  an  average  of  419  per  cc.  from 
40  samples  of  freshly  drawn  milk  taken  at  different  times  dur- 
ing a  year.  Some  very  careful  American  work  has  shown  that 
the  contamination  of  the  whole  milking,  mostly  from  within 
the  udder,  may  vary  from  200  per  cc.  to  900  per  cc.,  depending 
upon  the  cow,  the  average  being  about  500  per  cc.  The 
methods'  of  aseptic  production  of  milk  have  reached  such  a 
point  of  refinement  in  some  dairies  that  the  bacteria  unavoid- 
ably introduced  from  the  udder  constitute  the  bulk  of  the 
bacteria  present  in  the  product  when  bottled.  The  occurrence 
of  micrococci  and  streptococci  in  milk  in  the  udder  is  a  circum- 
stance that  certainly  cannot  justly  be  attributed  to  carelessness 
in  milk  production.  Nevertheless,  in  some  cases  the  contam- 
ination from  this  source  has  been  lessened  by  avoiding  the  use 


COAT  OF  ANIMAL.  5 

of  cows  with  leaky  teats.  Dr.  R.  G.  Freeman  has  found  that 
such  show  a  higher  bacterial  count  in  the  freshly  drawn  milk 
(67).  The  possibility  of  improvement  in  this  direction  is 
apparently  limited,  for  v.  Behring  reports  that  out  of  a  herd 
of  30  cows,  hardly  10%  approach  the  condition  of  the  theoret- 
ically perfect  cow,  i.e.,  one  having  no  bacteria  in  the  udder  (6). 

Foremilk.  The  very  first  stream  of  milk  from  the  teat  has 
been  found  to  contain  from  1,000  to  50,000  bacteria  per  cc. 
(26).  The  average  of  70  experiments  by  Conn  (10)  gives 
6,900  per  cc.  The  recognition  of  the  fact  that  the  first  streams 
of  milk  drawn  contain  more  bacteria  than  that  drawn  later 
suggested  the  practice  of  rejecting  the  first  stream  or  so,  to 
lower  the  general  bacterial  content  of  the  milking.  A  separate 
vessel  is  sometimes  provided,  to  avoid  the  necessity  of  drawing 
this  foremilk  upon  the  floor  of  the  stall.  The  whole  of  the 
milk  contains  more  or  less  bacteria  and  the  contamination  from 
the  first  milk  drawn  has  little  effect  upon  the  general  average. 
It  has  been  shown  that  the  rejection  of  three  streams  from  each 
teat  reduces  the  bacterial  content  of  the  whole  milking  by  4 
per  cent. ,  an  amount  practically  negligible  (60) .  The  rejection 
of  the  foremilk  is  practiced  much  more  generally  than  is  neces- 
sary, for  there  are  few  dairies  indeed  where  the  contamination 
from  the  foremilk  is  a  noticeable  factor  as  compared  with  that 
from  other  sources.  This  detail  is  a  survival  of  the  time  when 
it  was  universally  believed  that  the  contamination  in  milk  as 
drawn  was  derived  from  the  orifice  of  the  teat. 

Coat  of  animal.  The  excrement  and  mud  adhering  to  the 
hair  of  the  cow  constitute  a  most  abundant  source  of  contam- 
ination. The  amount  of  filth  carried  by  the  animal  is  greatly 
influenced  by  the  condition  of  the  barn-yard,  varying  with  the 
season.  Accumulations  of  manure  to  which  the  cows  have 
access,  aggravate  conditions.  Poor  location  of  barns  with  re- 
spect to  drainage  sometimes  creates  conditions  that  cannot  even 
be  alleviated  by  the  use  of  gravel  and  stone.  Instances  of  the 
paving  of  the  barn-yard  with  stone  and  with  cement  are  known. 
Currying  and  brushing  the  cows  is  effective,  and  should  be 
completed  at  least  half  an  hour  before  milking  is  begun.  Such 
a  period  of  time  permits  the  bacteria-laden  dust  to  settle  to  the 


6  THE  CONTAMINATION  OF  MILK. 

floor,  if  the  stable  be  free  from  draughts.  Brushing  just  before 
milking  will  usually  double  the  number  of  bacteria  that  would 
otherwise  have  gained  entrance  during  milking  (60).  In  the 
best  dairies  the  switch  of  the  tail  is  washed  before  the  milking. 
Precautions  are  taken  to  prevent  switching,  by  the  use  of  a  tail 
holder  (Ref.  8,  Chap.  IX). 

Exterior  of  udder.  The  udder  and  teats  are  especially  ex- 
posed to  filth,  either  from  the  barn-yard  or  the  stable  floor  when 
the  cow  is  lying  down.  The  movements  of  the  udder,  during 
milking,  tend  to  constantly  dislodge  dust  and  hair  which  fall 
into  the  milk  pail.  Dairy  practice  should  include  the  washing 
of  the  udder  and  teats  before  milking,  when  filth  is  present, 
and  the  dampening  of  the  hair  whether  dirt  is  present  or  not. 
If  the  udder  is  left  dripping  wet,  the  dirty  water  will  become 
a  source  of  contamination  of  the  milk.  The  dampening  causes 
the  dust  to  adhere  to  the  hair  and  largely  eliminates  an  im- 
portant contaminating  influence.  If  the  hair  of  the  udder  is 
kept  clipped  short,  the  cleaning  is  greatly 'facilitated.  The 
value  of  dampening  the  udder  may  be  demonstrated  by  a  simple 
bacteriological  experiment.  Sterile  Petri  dishes,  containing  a 
suitable  solid  culture  medium,  may  be  exposed  under  the 
udder  for  half  a  minute  during  milking  before  and  after  damp- 
ening. After  the  lapse  of  time  sufficient  to  permit  bacterial 
growth,  the  number  of  colonies  of  bacteria  showing  on  the 
two  plates  will  exhibit  a  wide  difference  in  the  number  present 
in  favor  of  dampening  (51).  The  number  of  bacteria  shaken 
from  apparently  clean  udders  may  be  reduced  by  two-thirds, 
by  merely  dampening.  The  possibilities  of  contamination, 
from  really  dirty  udders,  are  enormous.  By  dampening  the 
udder  and  flanks  the  contamination  may  be  reduced  to  about 
ten  percent,  of  that  which  would  otherwise  have  occurred  (60). 

In  the  certified  dairies  maintaining  the  greatest  aseptic  pre- 
cautions, the  methods  of  cleansing  the  udder  are  very  carefully 
considered.  Practice  varies,  but  the  following  method  will 
suffice  to  illustrate  the  point :  Wipe  udder  and  adjoining  parts 
with  burlap  to  remove  particles  of  bedding,  wash  with  luke- 
warm water  applied  with  a  cloth,  spray  with  lukewarm  water, 
wipe  W7ith  a  freshly  laundered  bath  towel.  This  is  so  folded 


SHAPE  OF  MILK  PAIL. 


that  one  towel  may  be  used  on  four  cows,  a  fresh  surface  being 
used  on  each  udder. 

After  cows  have  been  cleaned  before  milking  it  is  desirable 
to  prevent  their  lying  down  and  becoming  soiled.  A  cow 
kneels  on  the  fore  legs  before  lying  down,  and  a  light  chain 
passed  under  the  throat  and  affixed  to  the  stanchion  will  pre- 
vent her  doing  so. 

Shape  of  milk  pail.  Bacteriological  examinations  of  the 
foregoing  nature  have  suggested  modifications  in  the  shape  of 
the  milk  pail  to  minimize  the  contamination.  The  changes 
have  been  along  the  line  of  reducing  the  area  of  the  opening 
down  to  the  minimum  size  that  maybe  used  without  seriously 
inconveniencing  the  milker.  Fig.  2  shows  a  desirable  type 
of  milk  pail.  When  the  pail 
is  in  use,  the  hood  is  kept  up- 
permost, and  since  a  pail  is 
held  at  an  angle  to  the  floor, 
between  the  milker's  knees, 
the  hood  prevents  the  vertical 
exposure  of  the  opening.  Cov- 
ered pails  with  an  aperture, 
containing  a  cheesecloth  or  a 
wire  gauze  strainer,  are  infer- 
ior to  the  pail  with  the  small 
open  area  protected  by  a  hood. 
Such  a  pail  offers  a  greater 
area  open  to  contamination, 
and  the  strainer  does  not  con- 
stitute a  barrier  to  the  entrance 
of  bacteria.  Nevertheless  the 
covered  pail  with  cheesecloth 
strainer  is  very  convenient  for 
the  milker  and  is  a  great  im- 
provement over  the  common  •  Fig.  2.  Pearson's  milk  pail 
open  pail.  Such  a  pail  will  (Orig.}. 

exclude  29  per  cent,  of  the  total  bacteria  and  41  per  cent,  of 
lactic  acid  organisms  as  compared  with  the  ordinary  open  pail 
in  a  cleanly  dairy.  In  an  extremely  dirty  dairy  the  same  pail 


8  THE  CONTAMINATION  OF  MILK. 

(with  strainer)  will  exclude  as  high  as  97%  of  the  bacteria 
that  fall  into  the  common  open  pail  (59).  A  strainer  of 
absorbent  cotton  apparently  enmeshes  some  bacteria  and  keeps 
them  from  the  milk.  Tests  of  the  Gurler  pail  have  shown 
that  the  use  of  cotton  reduces  the  bacterial  count  to  30%  of 
that  obtained  when  the  pail  is  used  without  the  strainer  (61). 

The  milker.  The  milker  is  the  most  important  factor  in 
the  production  of  clean  milk.  Success  or  failure  depends 
upon  his  training  and  faithfulness  in  carrying  out  details,  the 
significance  of  which  he  may  not  appreciate  nor  respect. 
Milkers,  with  the  exception  of  a  very  few  in  model  dairies, 
trained  by  bacteriologists,  exhibit  a  low  degree  of  cleanliness 
in  their  work.  The  results  obtained  by  different  men,  working 
under  the  same  rules  for  asepsis,  are  striking.  A  group  of 
five  students  in  the  Connecticut  Agricultural  College,  trained 
in  the  theory  of  dairy  bacteriology,  were  able  to  draw  milk 
with  one-third  the  bacterial  content  of  that  drawn  by  the  two 
regular  milkers.  A  well  trained  college  graduate,  in  charge 
of  the  dairy  herd,  was  able  to  obtain  results  seven  times  as 
good  as  those  obtained  by  the  same  two  milkers  (60).  The 
practice  of  wetting  the  hands  with  milk,  which  afterwards 
drips  from  the  teat  into  the  pail,  is  far  from  uncommon.  It  is 
usually  not  the  practice  even  to  wash  the  hands  before  milking. 
The  practice  of  providing  clean  overalls  for  the  milkers  should 
be  more  general.  In  some  certified  dairies  the  milker  wears  a 
freshly  sterilized  suit  at  each  milking  period,  washes  his  hands 
after  milking  each  cow,  and  uses  a  sterilized  milking  stool. 
The  milker  as  a  factor  in  the  contamination  of  milk  with  the 
germs  of  the  infectious  diseases  of  man,  will  receive  consider- 
ation in  Chap.  III. 

Milking  machines.  The  advent  of  the  milking  machine  has 
been  welcomed  by  some,  with  the  idea  that  its  use  would 
practically  eliminate  the  sources  of  bacterial  contamination 
within  the  stable.  Hopes  in  this  direction  have  not  been 
entirely  realized.  The  machine  necessitates  bringing  milk  into 
contact  with  rubber  tubes,  which  have  long  been  recognized 
as  objectionable.  Rubber  is  very  difficult  to  cleanse  thoroughly, 
in  a  bacteriological  sense,  and  it  is  certain  that  the  care  given 


MILKING  MACHINES.  9 

by  the  average  dairyman  will  not  satisfy  requirements.  The 
complexity  of  the  apparatus  and  the  work  involved  in  taking 
the  machine  apart  twice  a  day  for  cleaning  and  scalding,  afford 
an  excuse  for  doing  it  but  once  a  day,  a  practice  which  cannot 
be  too  strongly  condemned.  Harrison  has  compared  hand 
milking  with  one  of  the  earlier  types  of  milking  machine  with 
the  result  that  the  machine  drawn  milk  was  found  to  contain 
from  three  to  twenty  times  the  number  of  bacteria  found  in 
hand  drawn  milk  (28).  Stocking  (62)  has  shown  the  infer-, 
iority  of  machine  drawn  milk  with  the  ordinary  care  given 
machines.  He  paid  particular  attention  to  methods  of  cleaning 
the  rubber  tubes,  and  by  the  exercise  of  elaborate  precautions, 
was  able  to  produce  results  favorable  to  the  machine.  The 
experiments  show  the  possibility  that  the  milking  machine,  in 
the  hands  of  an  exceptionally  careful  dairyman,  may  decrease 
the  pollution  of  milk.  Erf  (20)  made  similar  experiments 
with  the  care  of  the  rubber  parts  and  in  comparative  tests  of 
the  keeping  quality  was  able  to  show  results  in  favor  of  the 
machine.  Tests  of  milking  machines  usually  have  been  con- 
cerned chiefly  with  methods  of  caring  for  the  rubber  tubes  used 
with  the  machines.  It  has  been  found  necessary  to  keep  the 
tubes  in  an  antiseptic  solution  when  not  in  use.  Among  the 
substances  that  are  permissible  are  brine,  3%  formalin  solution 
or  lime  water  prepared  with  an  excess  of  fresh  unslacked  lime 
(30).  After  use  the  tubes  are  rinsed  in  cold  water,  then  with 
hot  water,  and  then  immersed  in  the  solution.  If  air  remains 
in  any  portion  of  the  tubes,  bacteria  will  multiply  at  that  point. 
Before  use  on  the  cow,  the  tubes  must  be  thoroughly  rinsed 
with  hot  water  to  remove  the  antiseptic.  If  formalin  is  used 
as  an  antiseptic  there  is  always  the  possibility  that  it  will  not 
be  rinsed  out  thoroughly, — either  through  carelessness  or  inten- 
tion. On  this  account  the  use  of  this  common  milk  preserv- 
ative should  be  interdicted.  The  use  of  the  milking  machine 
ought  to  lessen  the  danger  from  the  contamination  of  milk  by 
the  germs  of  infectious  diseases  of  man,  for  it  eliminates  one 
of  the  stages  in  milk  handling  during  which  persons  come  in 
close  contact  with  the  milk.  Nevertheless,  there  are  many 
other  sources  for  possible  infection  of  milk  from  diseased  per- 


10  THE  CONTAMINATION  OF  MILK. 

sons.  The  milking  machine  increases  rather  than  lessens  the 
possibility  of  ordinary  contamination, -and,  so  long  as  rubber  is 
used  in  its  construction,  it  cannot  be  regarded  as  a  simple 
means  for  avoiding  contamination. 

Stable.  The  construction  of  the  building  and  its  condi- 
tion as  regards  cleanliness  are  important  factors  in  milk  pro- 
duction. The  desirable  sanitary  features  in  a  stable  are  those 
contributing  to  easy  cleaning,  freedom  from  dust,  good  venti- 
lation and  abundant  lighting.  A  one-story  structure  obviates 
the  undesirable  features  of  the  ordinary  dusty  ceiling  with  hay 


Fig.  J,     A  convenient  stable. 

loft  above,  and,  further,  usually  contributes  to  better  ventila- 
tion. Conditions  permitting  draughts  of  air,  which  stir  up 
dust,  are  to  be  avoided:  Fig.  3  shows  a  convenient  stable. 
Note  the  suspended  railway  track,  by  means  of  which  the 
manure  is  removed  in 'buckets  to  a  wagon.  The  railway  is 
used  in  a  similar  way  to  bring  in  feed. 

Floor.  Cement  is  vastly  preferable  to  wood  as  a  floor,  for  it 
cannot  become  saturated  with  filth  to  give  rise  to  offensive 
odors.  By  accurate  construction  of  the  gutter  behind  the 
cows,  drainage  conditions  may  be  made  perfect.  A  rough 
sandpaper  finish  obviates  the  danger  of  cows  slipping.  Planer 
shavings  (17),  as  bedding,  offer  the  minimum  of  possibility 


STABLE  .  11 

of  bacterial  contamination,  but  the  use  of  this  material  must 
of  necessity  be  restricted  to  a  very  few  of  the  best  dairies. 

Mangers  and  stanchions.  Wooden  mangers,  when  old,  be- 
come harboring  places  for  decomposing  feed,  especially  if  in- 
dividual compartments  are  provided  for  each  cow.  Ease  of 
cleaning  has  resulted  in  the  general  use  of  one  continuous 
cement  trough  for  the  whole  row  of  cows.  Separate  cement 
mangers,  if  the  cows  are  habituated  to  taking  certain  places, 
would  have  a  slight  tendency  to  restrain  the  spread  of  bovine 
tuberculosis.  In  the  best  stables,  wooden  stanchions'  have 
been  supplanted  by  a  variety  of  iron  devices.  The  stanchions 
should  be  spaced  from  three  to  three  and  one-half  feet  from 
center  to  center,  at  the  least,  in  order  to  give  room  between 
cows.  The  swing  stanchion  is  preferable,  because  it  restricts 
movement  forward  and  backward  and  thus  contributes  to  the 
cleanliness  of  the  cow  (65). 

Barn  improvements.  The  general  use  of  the  model  dairy 
barn  in  milk  production  cannot  be  brought  about  immediately. 
Therefore  at  present  we  have  the  problem  of  adapting  the  older 
inferior  structures  to  the  requirements  of  clean  milk  produc-' 
tion.  Fortunately,  with  slight  structural  changes  and  the  'ex- 
ercise of  -care,  milk  of  a  very  satisfactory  sanitary  quality  may' 
be  produced  in  such  barns.  The  condition  of  the  ordinary 
wooden  floor  may  be  greatly  improved  by  the  use  of  land  plas- 
ter or  sawdust  as  an  absorbent  of  liquids.  Changes  for  im- 
proving the  lighting  and  ventilation  are  usually  possible.  '  Ven- 
tilation, most  important  in  cold  climates  where  cattle  are'  shel- 
tered in  the  stable,  becomes  a  negligible  factor  in  mild  climates 
where  the  cattle  are  kept  indoors  only  during  milking.  The 
accumulation  of  manure  near  the  building  may  be  avoided 
by  keeping  a  wagon  convenient  for  loading  directly  from  the 
stable.  At  certain  seasons  the  manure  may  be  carted  directly 
to  the  fields,  and,  at  other  times,  to  a  satisfactory  distance  from 
the  barn.  Whitewashing  is  one  of  thejnost  popular 


for  improving  interior  conditions.  Its  occasional  application 
with  a  brush  removes,  for  the  time  being,  much  dust  arid  cob- 
webs, besides  improving  the  lighting.  It  is  fairly  efficient  for 
disinfecting  purposes,  some  other  agents  being  more  active. 


12  THE  CONTAMINATION  OF  MILK. 

Feeding.  The  dust  in  the  air  occasioned  by  the  feeding  of 
grain  and  hay,  during  the  milking,  increases  the  bacterial  con- 
tent of  the  milk  drawn  during  the  feeding  by  about  one-third 
of  that  of  cows  milked  when  not  feeding,  other  conditions  be- 
ing alike.  The  feeding  of  dry  corn  stover,  immediately  before 
milking,  also  increases  the  contamination  to  about  threefold 
of  that  occurring  without  such  source  of  dust  in  the  air  (60). 

Feeding  hay  during  the  milking  period  is  a  common  practice 
by  no  means  necessary.  Cows  accustomed  to  at  least  eating 
grain  at  that  time  require  considerable  training  before  they 
will  patiently  wait  until  after  milking  for  their  feed.  Delay 
in  feeding  in  some  cases  undoubtedly  adds  some  extra  trouble 
to  the  attendants,  but  is  practiced  in  the  best  dairies. 

Certain  feeds  are  highly  objectionable  because  of  their  effect 
upon  the  cow.  Brewers'  grains,  distillers'  grains,  and  sugar- 
beet  pulp  are  a  cheap  source  of  feed  in  certain  localities,  and 
they  are  fed  in  great  quantity  long  after  attaining  an  advanced 
stage  of  fermentation.  The  result  is  a  chronic  diarrhea  in 
the  cows  and  conditions  in  the  stable  that  prevent  the  drawing 
of  clean  milk.  It  is  not  at  all  unlikely  that  milk  from  cows 
almost  exclusively  fed  on  such  highly  fermented  food,  would 
contain  substances  not  found  in  the  milk  of  cows  consuming 
wholesome  feed.  On  the  other  hand,  the  use  of  limited  quan- 
tities of  beet  pulp  and  the  like,  when  fresh  and  combined  with 
a  properly  balanced  ration,  seems  to  cause  no  trouble.  These 
products,  when  dried,  are  unobjectionable  (37). 

Special  milking  rooms.  Efforts  to  reduce  bacterial  contam- 
ination to  the  minimum  have,  in  some  dairies,  led  to  the  con- 
struction of  a  milking  room  apart  from  the  general  stable  where 
better  aseptic  conditions  might  be  maintained.  Such  construc- 
tion as  to  permit  sterilization  of  the  walls,  floor  and  ceiling, 
together  with  the  absence  of  the  contaminating  features  of 
feeding  and  manure,  offered  hope  of  reducing  bacterial  contam- 
ination. Such  rooms  are  necessarily  small  and  a  few  cows  at 
a  time  are  admitted.  Results  have  been  disappointing,  for  the 
movements  of  the  cattle  dislodge  the  dust  from  the  hair  and 
result  in  a  higher  bacterial  content  of  the  air  than  in  the  general 
stable  where  the  cattle  stand  quietly.  An  open  shed  in  a  pas- 


CLEANSING  OF  UTENSILS.  13 

ture  offers  the  best  conditions  for  milking,  as  regards  the  con- 
tamination from  air. 

Cleansing:  of  utensils.  The  proper  care  of  the  vessels  with 
which  milk  comes  in  contact  is  an  important  factor  in  reducing 
contamination.  No  precaution  for  producing  good  milk  is 
more  easily  carried  out,  yet  none  is  more  generally  neglected. 
Rinsing  in  cold  or  lukewarm  water  is  necessary  first  to  remove 
the  milk.  If  hot  water  is  used  at  first  it  will  render  cleaning 
difficult  by  causing  some  of  the  milk  constituents  to  adhere  to 
the  utensils.  This  preliminary  step  is  followed  by  scrubbing 
with  hot  water  containing  soap  powder  or  some  alkali  (16,  58), 
and  this  in  turn  by  rinsing  in  hot  water.  The  practice  of 
merely  rinsing  utensils  without  washing  and  scalding,  after 
the  night's  milking,  and  then  using  them  the  next  morning,  is 
intolerable. 

Scalding.  Too  often,  the  final  rinsing  in  hot  water  is  con- 
sidered sufficient.  Bacteriological  requirements,  however, 
demand  the  more  thorough  application  of  heat.  Harrison  (28) 
and  Russell  (50)  have  shown  the  inefficiency  of  the  ordinary 
haphazard  scalding.  To  insure  complete  destruction  of  all  bac- 
teria,— that  is,  sterilization, — requires  that  the  utensils  be  sub- 
jected to  steam  under  pressure  of  at  least  five  pounds  for  twenty 
minutes.  Fig.  4  shows  the  apparatus  used  for  this  purpose, 
containing  a  car  used  for  milk  bottles.  This  method  of  heating 
utensils  is  the  only  one  that  may  properly  be  designated  as  ster- 
ilization. The  others  do  not  sterilize,  as  they  do  not  result  in 
the  death  of  all  the  spores  of  bacteria.  Very  excellent  results 
may  be  obtained  by  subjecting  the  utensils  to  the  action  of  steam 
in  a  closed  chamber,  but  not  under  pressure.  La  Grange  (38) 
tested  the  effectiveness  of  such  a  piece  of  apparatus,  finding  that 
99.2%  of  all  bacteria  in  milk  bottles  were  killed .  Those  surviv- 
ing were  spore-bearing  organisms.  To  obtain  this  result  the 
steam  was  admitted  to  the  room  for  fifty-five  minutes,  about 
.half  of  this  period  having  elapsed  before  the  temperature  reached 
the  boiling  point.  It  is  the  more  common  practice  to  scald 
utensils  over  a  jet  of  steam,  one  by  one.  La  Grange  used  steam 
from  a  half -inch  pipe,  under  a  pressure  of  thirty  pounds,  and 
with  a  duration  of  fifteen  seconds  obtained  results  as  satisfac- 


14  THE  CONTAMINATION  OF  MILK. 

tory  as  by  the  other  method  tested  by  him.  When  the  oper- 
ator is  in  a  hurry,  and  shortens  the  exposure  down  to  three 
seconds,  the  efficiency  of  the  method  is  open  to  question.  The 
machine  in  which  bottles,  in  an  inverted  position,  are  passed 


fig.  4.     Sterilizer  containing  racks  for  Jwlding  bottles. 

over  steam  jets,  likewise  does  poor  work,  unless  its  speed  is  so 
slackened  as  to  reduce  its  rated  output  (54).  Boiler  scale  com- 
pounds, or  oil  in  the  feed  water,  may  so  taint  the  steam  that 
an  objectionable  odor  will  be  transmitted  to  the  cans  or  bottles 
and  thence  to  the  milk  or  cream. 


HANDLING  MILK.  15 

Boiling  water  must  of  necessity  be  used  by  the  smaller  pro- 
ducers. If  it  is  provided  in  sufficient  amount  and  used  with  a 
recognition  of  the  fact  that  time  of  exposure,  as  well  as  temper- 
ature, is  a  factor  in  killing  bacteria,  excellent  results  may  be 
obtained.  A  large  caldron  should  be  provided  in  which  such 
articles  as  strainers  and  coolers  could  be -immersed  for  several 
minutes.  Cans  should  be  filled  with  boiling  water  and  allowed 
to  stand  for  some  minutes  before  being  emptied.  After  scald- 
ing and  draining,  utensils  should  be  kept  in  a  place  protected 
from  contamination  by  dirt. 

The  cooler  permanently  installed,  and  too  large  to  place  in  a 
sterilizer,  is  scalded  properly  with  great  difficulty.  The  use  of 
streaming  steam,  applied  with  a  hose,  is  a  tedious  process,  which 
invites  carelessness  on  the  part  of  the  man  doing  the  work. 

Construction  of  utensils.  Cracks  or  seams  of  utensils  and 
rust  spots  afford  points  for  the  lodgment  of  milk,  which 'accu- 
mulates in  spite  of  washing,  and  contributes  to  contamination. 
Seamless  pails  are  preferable,  but  if  joints  are  present  they 
should  be  flushed  with  solder.  Metallic  strainers  are  the  worst 
offenders  in  this  respect.  Valves  are  a  necessary  evil,  as  con- 
stant vigilance  is  necessary  to  keep  them  clean.  Pipe  offers 
exceptional  difficulties  in  the  way  of  cleaning  and  scalding, 
while  rubber  hose  is  even  worse.  The  use  of  wood  anywhere 
that  milk  will  come  in  contact  with  it,  is  very  undesirable,  on 
account  of  the  impossibility  of  cleansing  it  properly.  Wooden 
plugs  for  milk  cans  are  still  used  in  New  England  in  spite  of 
their  unsanitary  qualities. 

Handling1  milk.  Immediately  after  drawing,  milk  is  strained 
and  passed  over  a  piece  of  apparatus  for  the  purpose  of  cooling 
and  aerating.  Uncleanliness  of  the  apparatus  or  its  location 
in  dusty  air,  offer  opportunities  for  contamination.  Straining 
through  cotton  cloth  does  not  remove  bacteria  (12,  14);  on 
the  contrary,  it  may  add  them  if  the  apparatus  is  not  sterile. 
Absorbent  cotton,  between  layers  of  cheesecloth,  is  the  most 
satisfactory  medium  for  removing  visible  filth  from  milk. 
Clean  cheesecloth  alone  is  preferable  to  the  wire  strainer  in 
its  usual  dirty  condition.  Milk  coolers  practically  all  work 
on  the  principle  of  bringing  milk  in  contact  with  surfaces 


16  THE  CONTAMINATION  OF  MILK. 

cooled  by  water.  There  may  be  a  water  leak  in  the  apparatus, 
causing  contamination  from  that  source.  Milk  cans  are  fre- 
quently stood  in  tanks  of  water,  for  cooling,  and  splashing 
may  cause  water  to  reach  the  milk.  The  practice  of  adulter- 
ating milk  with  water  is  common  enough  to  deserve  note  as  a 
source  of  contamination.  Bergey  (8)  has  given  figures  show- 
ing the  increase  in  the  bacteria  of  milk  at  different  stages  in 
handling,  derived  from  various  utensils. 

Bottling  milk.  The  filling  of  milk  bottles  in  the  larger  dairies 
is  done  rapidly  by  the  use  of  a  bottling  machine.  In  some 
cases  a  machine  is  used  which  also  places  the  paper  caps  in 
position.  This  is  desirable,  from  a  hygienic  point  of  view, 
because  it  eliminates  the  dangers  associated  with  the  handling 
of  the  paper  caps  when  this  is  done  by  a  man.  When  the 
machine  is  used,  the  caps  are  sterilized  before  using.  When 
bottles  are  capped  by  hand  danger  from  contamination  by  the 
workman  may  be  minimized  by  the  use  of  a  special  copper 
tube  with  a  slit  on  two  sides.  The  caps  are  stacked  in  this 
tube  when  sterilized,  after  which  they  are  removed  and  used 
by  touching  the  edges  only  (Ref.  8,  Chap.  IX). 

Milk  room.  The  cooling  and  subsequent  manipulation  of 
the  milk  should  be  carried  on  under  conditions  as  free  as  pos- 
sible from  the  influence  of  dusty  air.  A  room  or  building  sep- 
arate from  the  stable  should  be  provided  for  the  purpose.  A 
cement  floor,  screened  windows  and  ease  of  cleaning  are  desir- 
able features  of  such  a  structure.  In  the  best  dairies  admit- 
tance to  the  milk  room  is  denied  to  the  milker  and  even  visit- 
ors. Elaborate  precautions  are  taken  to  prevent  contamination 
of  the  milk  during  straining,  etc.,  even  the  air  being  freed 
from  bacteria  before  entering  the  room  through  the  ventilating 
system. 

Delivery  of  milk.  Bacteriological  considerations  lead  to  the 
conclusion  that  delivery  in  sterile  bottles,  filled  at  the  dairy, 
offers  the  least  possibility  of  contamination  in  transit.  But 
the  milk  bottles  must  be  cleaned  and  heated  well  before  use, 
if  for  no  other  reason  than  the  fact  that  milk  bottles  are  put  to 
disgusting  uses  in  some  households.  Bottled  milk  is  not  always 
what  it  should  be,  as  for  instance  when  the  driver  fills  a  dirty 


SEDIMENTS.  17 

bottle  on  the  wagon  to  satisfy  a  customer's  demand  for  ' '  bottled 
milk."  Dipping  or  pouring  from  delivery  cans  multiplies  the 
possibilities  for  the  entrance  of  bacteria. 

Paper  bottles  used  but  once  would  avoid  some  of  the  dan- 
gers attributable  to  the  use  of  glass  bottles  (57).  They  have 
been  before  the  public  for  some  time,  but  apparently  their  dis- 
advantages outweigh  the  advantages,  for  they  have  hot  come 
into  general  use. 

Milk  flavors.  Care  must  be  exercised  in  the  production 
of  milk  to  avoid  certain  undesirable  flavors  in  the  product. 
Garlic,  onion,  turnip,  when  fed  before  milking,  will  taint  the 
milk.  Experiments  have  shown  that  the  feeding  of  anise, 
fennel  and  garlic,  taints  the  milk  through  the  excretion  of  the 
flavoring  substances  by  the  udder  ( 19) .  Similar  considerations 
point  to  the  necessity  of  care  in  the  administration  of  drugs  to 
milch  cowrs,  for  fear  of  transmitting  the  drug  to  the  milk. 
Backhaus  (3)  regards  the  influence  of  food  on  the  flavor  and 
wholesomeness  of  milk,  through  this  channel,  as  unimportant. 
Warm  milk  absorbs  odors  from  stable  air  more  quickly  than 
cold  milk.  It  has  been  shown  that  exposure  from  one-half  hour 
to  an  hour  and  a  half  at  57°-72°F.  to  the  odor  of  either  corn 
silage,  horse  manure,  oils  of  cinnamon,  wintergreen  or  pepper- 
mint, will  impart  the  characteristic  odor  to  milk  (52).  Fresh 
urine  also  imparts  an  odor,  absorbed  from  the  air.  Particles 
of  manure  by  dissolving  in  the  milk  impart  a  flavor.  The 
flavors  from  silage  and  alfalfa  are  not  at  all  offensive,  and  milk 
consumers  become  accustomed  to  them.  The  process  of  aerat- 
ing milk  remedies  such  defects  (39).  Aeration  is  not  necessary 
when  milk  is  drawn  under  the  very  best  conditions. 

Sediments.  The  deposit  in  milk,  consisting  of  mud,  feces, 
hair,  etc.,  all  too  common  in  milk  as  delivered  to  the  cus- 
tomer, bears  witness  to  the  carelessness  in  milking  (35,  36). 
Straining  removes  much  of  the  coarse  material,  but  it  is  fre- 
quently found  necessary  to  resort  to  a  more  effective  process. 
The  milk  is  run  through  a  cream  separator  for  the  purpose  of 
removing  the  foreign  matter  by  the  action  of  centrifugal  force. 
It  is  effective,  so  far  as  dirt,  etc.,  is  concerned,  but  not  in  the 
case  of  the  bacteria,  which  largely  remain  in  the  milk  (43). 


18  THE  CONTAMINATION  OF  MILK. 

Iii  fact,  passing  milk  through  a  centrifugal  machine  increases 
the  apparent  number  of  bacteria  by  separating  the  clumps  (55, 
56). 


REFERENCES. 

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2.  BACKHAUS  und  APPEI,.     Ueber  aseptische  Milchgewinnung.     II, 
Ber.  Landw.  Inst.  Univ.  Konigsb,  V,  1898-1899,  S.  73. 

3.  BACKHAUS.     Einfluss  des  Putters  und  der  Individualitat  der  Milch- 
kuh  auf  Geschmack  und  Bekommlichkeit  der  Milch.    Ber.  Landw.  Inst. 
Univ.  Konigsb.,  V,  1898-1899,  S.  110. 

4.  BACKHAUS  und  APPEIV.     Ueber  aseptische  Milchgewinnung.     Ber, 
Landw.  Inst.  Univ.  Konigsb.,  1903. 

5.  EARTHED.     Recherches  sur  les  microorganismes  de  1'air  des  etables, 
du  lait  au  moment  de  la  traite  et  de  la  mamelle.    Rev.  Gen.  Lait,  lre 
Ann£e,  1902,  No.  23,  p.  529. 

6.  BEHRING.     Suppression  of  tuberculosis  in  cattle  and  the  hygienic 
production  of  milk.     Paper  read  at  the  XXXIV  Plenary  Meeting  of  the 
German  Agricultural  Council. 

7.  BELCHER.     Clean  milk.     New  York :  The  Hardy  Publishing  Co., 
1903. 

8.  BERGEY.     Sanitary  supervision  of  the  collection  and  marketing  of 
milk.     Univ.  of  Penn.  Med.  Bui.,  July- August,  1904. 

9.  BURR.     The  source  of  acid  organisms  of  milk  and  cream.     Centbl. 
Bakt.,  etc.,  2  Abt.,  Bd.  VIII,  1902,  No.  8,  S.  236. 

10.  CONN.     Bacteria  in  freshly  drawn  milk.     Fifteenth  Ann.  Rept. 
Storrs  Agr.  Exp.  Sta.,  Storrs,  Conn.,  1903,  p.  92. 

11.  CONN,  ESTEN   and   STOCKING.     Classification   of  dairy  bacteria. 
Eighteenth  Ann.  Rept.    Storrs  Agr.  Exp.  Sta.,  Storrs,   Conn.,    1906, 
p.  91. 

12.  CONN  and   STOCKING.     Comparison  of  bacteria  in  strained  and 
unstrained  samples  of  milk.     Fifteenth  Ann.  Rept.  Storrs  Agr.  Exp. 
Sta.,  Storrs,  Conn.,  1903,  p.  33. 

13.  CONN  and  STOCKING.    Aseptic  milk.    Fifteenth  Ann.  Rept.  Storrs 
Agr.  Exp.  Sta.,  Storrs,  Conn.,  1903,  p.  52. 

14.  CONN  and  STOCKING.     Strained  and  unstrained  milk  preserved 
at  70°  and  50°.     Fifteenth  Ann.  Rept.  Storrs  Agr.  Exp.  Sta.,  Storrs, 
Conn.,  1903,  p.  38. 


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U.  S.  Dept.  Agr.,  Washington,  D.  C.,  1906. 

16.  DOANE.     The  disinfectant  properties  of  washing  powders.     Bui. 
No.  79,  Maryland  Agr.  Exp.  Sta.,  College  Park,  Md.,  1902. 

17.  DOANE.     Tests  of  materials  for  bedding  cows.     Bui.  No.  104, 
Maryland  Agr.  Exp.  Sta.,  College  Park,  Md.,  1905. 

18.  D'Hiui,.     Zeitschr.  Fleisch  u.  Milchhyg.,  1905,  S.  84;  also,  Jour, 
of  Compar.  Path,  and  Ther.,  Vol  XIX,  1906,  p.  50. 

19.  DROMBROWSKI.     Some   experiments  on  the  passage  of  odorifer- 
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20.  ERF.     Milking  machines.     Bui.  No.  HO,  Kansas  State  Agr.  Col. 
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21.  FORD.      The    bacteriology  .of    healthy    organs.       Trans.    Assoc. 
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23.  FRASER.     City  milk  supply.  '   Bui.  No.  92,   Univ.  of  III.  Agr. 
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24.  FRASER.     Effect  of  corn  silage  on  the  flavor  of  milk.     Bui.  No. 
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25.  FREUDENREICH.     Ueber  das  Vorkommen  von  Bakterien  im  Kuh- 
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26.  FREUDENREICH.    Ueber  die  Bakterien  im  Kuheuter  und  ihre  Ver- 
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27.  FREUDENREICH  und' THONI.    Uber  die  in  der  normalen  Milch  vor- 
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31.  HENDERSON.     A  contribution  to  the  study  of  mastitis  in  cows. 
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20  THE  CONTAMINATION  OF  MILK. 

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the  same  to  the  keeping  quality  of  milk.     Eleventh  Ann.  Rept.  Agr. 
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52.  RUSSEW*.     Relative  absorption  of  odors  in  warm  and  cold  milk. 
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53.  RusSEUv  and   HASTINGS.     Disappearance  of  bacteria  artificially 
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54.  RUSSEXI,  and  HOFFMANN.     Bacteriological  test  of  a  bottle-wash- 
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55.  SEVERIN.     Vermindert  die  Zentrifugierung  die  Bakterienzahl  in 
der  Milch?     Centbl.  Bakt.,  etc.,  2  Abt.,  Bd.  XIV,  1905,  S.  605. 

56.  SEVERIN  and   BUDINOFF.      Contribution   to  the  bacteriology  of 
milk.     Centbl.  Bakt.,  etc.,  2  Abt.,  Bd.  14,  1905,  S.  463. 

57.  STEWART.     The  single  service  milk  bottle;   its  advantages  and 
adaptability  for  general  use.     Sanitation,  December,  1904. 

58.  STEWART.     Cleansing  of  milk  vessels  :  relative  value  of  washing 
powders.     Amer.  Med.,  Vol.  XI,  1906,  No.  7,  p.  241. 

59.  STOCKING.     Efficiency  of  a  covered   pail   in   excluding  filth  and 
bacteria   from  milk.      Foiirteenth  Ann.  Rept.  Storrs  Agr.  Exp.  Sta., 
Storrs,  Conn.,  1901,  p.  105. 

60.  STOCKING.     Quality  of  milk  as  affected  by  common  dairy  prac- 
tices.    Eighteenth  Ann.  Rept.  Storrs  Agr.  Exp.  Sta.,  Storrs,  Conn., 
1906,  p.  66. 

61.  STOCKING.     Comparative  studies  with  covered  milk  pails.     Bui. 
No.  48,  Storrs  Agr.  Exp.  Sta.,  Storrs,  Conn.,  1907. 

62.  STOCKING.     Bacteriological  studies  of  a  milking  machine.     Bui. 
No.  92,  Bur.  Anim.  Ind.,  U.  S.  Dept.  Agr.,  Washington,  D.  C.,  1907. 

63.  STOCKING  and  MASON.     Milking  machines.     Effect  upon  quality 
of  milk.     Bui.  No.  47,  Storrs  Agr.  Exp.  Sta.,  Storrs,  Conn.,  May,  1907. 

64.  SWITHINBANK  and  NEWMAN.     The  bacteriology  of  milk.     L/on- 
don  :  J.  Murray,  1903. 

65.  TRUEMAN.     Improving  dairy  conditions.      Bui.   No.  53,  Storrs 
Agr.  Exp.  Sta.,  Storrs,  Conn.,  1908. 

66.  WARD.     The  persistence  of  bacteria  in  the  milk  ducts  of  the  cow's 
udder.    Jour.  Appl.  Micros,  and  Lab.  Methods,  Vol.  I,  No.  12,  1898, 
p.  205. 

67.  WARD.     The  invasion  of  the  udder  by  bacteria.     Bui.  No.  178, 
Cornell  Univ.  Agr.  Exp.  Sta.,  Ithaca,  N.  Y.,  1900. 


22  THE  CONTAMINATION  OF  MILK. 

68.  WiiyLEM  et  MINNE.       La   traite   peut-elle   fournir   du  lait  asep- 
tique?     Rev.  Gen.  Lait,  4e  Annexe,  1904,  No.  6,  p.  121. 

69.  WIU.EM  et  MiELE.     Essais  de  traite  aseptique.    Rev.  Gen.  Lait, 
4e  Annee,  1905,  No.  18,  p.  409. 

70.  WII.I.OUGHBY.      Milk,  its  production  and  uses.    Ivondon  :  Charles 
Griffin  &  Company,  Ltd.,  1903. 

71.  WINSI.OW.     The  production  and   handling  of  clean  milk.     New 
York:     Wm.  R.  Jenkins  Co. 


CHAPTER  II. 


CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 


Significance  of  bacterial  contamination.  The  mere  consid- 
eration of  the  multiple  sources  of  contamination  of  milk,  em- 
phasizes the  truth  of  the  statement  that  freshly  drawn  milk 
contains  a  wide  variety  of  bacterial  forms.  Certainly  no  food 
used  so  universally  by  man  is  exposed  during  its  preparation 
to  a  greater  variety  of  contaminating  influences.  The  signifi- 
cance of  these  bacteria  in  the  subsequent  changes  in  milk  de- 
pends upon  their  character,  adaptability  for.  existence  in  milk, 
and  upon  the  conditions  under  which  milk  is  kept.  The  pre- 
cautions exercised  in  restricting  the  growth  of  bacteria  are  of 
greater  importance  in  controlling  the  character  of  the  milk 
when  consumed,  than  those  exercised  to  prevent  the  initial 
contamination.  The  results  of  changes  of  bacterial  origin  in 
milk,  concern  not  merely  the  commercial  requirements  that 
it  must  be  unaltered  in  taste  and  appearance  when  consumed, 
but  also  have  a  direct  bearing  upon  the  hygiene  of  food. 

The  constituents  of  milk  and  the  form  in  which  they  exist, 
together  with  the  temperatures  to  which  milk  is  exposed,  offer 
conditions  favorable  to  the  growth  of  quite  a  variety  of  bac- 
terial groups.  The  carbohydrates  represented  by  the  milk 
sugar  are  present  in  solution,  a  most  favorable  form  for  bac- 
terial nutrition.  The  albuminous  constituents,  either  in  solu- 
tion or  in  a  finely  divided  state  in  suspension,  are  likewise 
freely  available  to  satisfy  bacterial  requirements. 

Fat  alone,  of  the  constituents  of  milk,  resists  the  action  of 
the  common  bacteria  found  in  milk.  When  consideration  is 
paid  to  the  rapidity  of  the  growth  of  bacteria,  and  to  the  fact 
that  decomposition  of  organic  matter  is  the  chief  function  of 
bacteria  as  a  class,  the  full  significance  of  the  vulnerability  of 
milk  becomes  apparent. 


24  CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

Under  favorable  conditions  of  food,  temperature,  environ- 
ment, etc.,  the  possibilities  of  bacterial  multiplication  are  enor- 
mous. The  temperatures  to  which  milk  is  exposed  in  the 
summer,  when  not  refrigerated,  are  highly  favorable  to  their 
multiplication. 

Numbers  of  bacteria  in  market  milk.  Hill  and  Slack  (19) 
have  tabulated  results  of  examination  of  2,394  samples  of  milk 
in  Boston,  covering  a  period  of  four  months  (June  to  Sep- 
tember), with  results  as  follows  : 

TABLE  I. 
BACTERIA  IN  BOSTON  MILK.  Per  cent. 

Below  100,000  bacteria  per  cc.  ...  42. 

Between  100,000  and  500,000  per  cc.  ..'.  ...  29.75 

Between  500,000  and  1,000,000  per  cc..  9.75 

Between  1,000,000  and  5,000,000  per  cc.  ...  ..  12.75 

Above  5,000,000  per  cc...                                                                        5. 
Uncountable  plates ' 75 

These  figures  are  not  exceptionally  high,  but  are  good  as 
compared  with  others.  Bacterial  counts  running  into  the 
millions  are  common  in  hot  weather.  Rosenau  (34)  found 
that  the  milk  of  Washington,  D.  C.,  averaged  22,134,000  bac- 
teria per  cc.  in  1906  and  11,270,000  per  cc.  in  1907  during  the 
months  of  July,  August  and  September.  This 'writer  gives  a 
resum£  of  results  of  similar  work  done  elsewhere. 

Effect  of  temperature  on  bacterial  growth.  At  1°C.  (34°F.) 
bacterial  growth  is  very  powerfully  restrained  for  awhile.  Milk, 
after  six  or  eight  days  at  this  temperature,  may  show  less  bac- 
teria than  when  freshly  drawn.  The  circumstance  is  attribut- 
able to  the  "germicidal  "  phenomenon  of  milk.  Pennington 
(32)  in  the  study  of  samples  of  milk  kept  for  long  periods  at 
1°C.  found  that  certain  bacteria  multiply  at  that  temperature. 
In  time  the  numbers  may  run  into  the  millions  per  cc.  The 
species  belonged  to  the  group  of  organisms  capable  of  acting  on 
protein,  without  affecting  the  appearance  of  the  milk.  These 
observations  were  made  upon  the  best  milk  obtainable,  as  well 
as  upon  poor  milk.  It  must  be  concluded  that  cold  storage 
cannot  be  relied  upon  to  keep  milk  indefinitely.  At  10°C. 
(50°F.)  milk  may  be  kept  for  two  or  three  days  without  an 


EFFECT  OF  TEMPERATURE  ON  BACTERIAL  GROWTH.         25 

increase  in  numbers,  and  those  growing  at  that  temperature 
not  lactic  acid  bacteria.  At  20°C.  (68°F.)  milk  sours  in  forty 
hours.  At  37°C.  (99°F.)  curdling  occurs  in  a  few  hours  (ll). 
The  length  of  time  required  for  transportation  and  delivery  of 
milk  is  frequently  such  that  refrigeration  must  be  used  to  insure 
its  reaching  the  consumer  in  proper  condition. 

Methods  of  cooling.  Some  of  the  methods  on  the  farm  are 
crude  and  inefficient.  The  process  of  passing  mrlk  through 
the  air  to  remove  undesirable  odors — aeration — will  accomplish 
some  reduction  of  temperature.  Cans  of  milk  may  be  stood 
in  a  tank  of  water,  and  by  stirring  the  milk  occasionally  the 
temperature  may  be  reduced.  In  a  hot  dry  climate  cans  may 
be  covered  with  burlap  and  dampened.  The  evaporation  from 
the  burlap  will  lower  temperature.  In  the  same  way,  wet 
blankets  over  cans  on  a  wagon  are  of  use. 

There  are  various  mechanical  devices  for  utilizing  cold  water. 
These  fail  in  hot  weather,  when  most  needed.  The  use  of  ice 
with  proper  apparatus  is  productive  of  better  results,  and  is 
essential  in  hot  weather.  The  use  of  ice  constitutes  the  stand- 
ard, approved  method  of  cooling  milk  on  the  small  dairy  farm, 
in  climates  where  natural  ice  may  be  obtained. 

Mechanical  refrigeration,  by  means  of  anhydrous  ammonia  or 
carbon  dioxide,  furnishes  the  most  efficient  means  for  preserv- 
ing milk  in  large  quantities  (38).  It  is  employed  in  city 
distributing  depots,  and  in  the  best  large  dairies.  It  may,  and 
should,  be  very  widely  used  in  connection  with  dairies  in  warm 
climates. 

Milk  during  transportation.  The  refrigerator  car,  with 
abundant  ice  supply,  solves  the  problem  of  shipping  milk  long 
distances  in  tanks.  It  is  not  so  effective  for  local  traffic,  when 
the  car  doors  are  frequently  opened. 

Bottles  of  milk  in  crates  may  be  kept  in  good  condition  for 
quite  a  time  without  a  refrigerator  car,  by  packing  cracked  ice 
about  them.  Bottles  of  certified  milk,  packed  in  closed  wooden 
boxes,  perhaps  metal  lined,  and  thoroughly  surrounded  with 
cracked  ice,  may  likewise  be  shipped.  Milk  in  cans  covered 
with  non-conducting  jackets  of  hair  may  be  kept  cool  longer 
than  otherwise  (4,  14,  43,  44). 


26  CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

Preservation  by  chemicals.  Bacterial  changes  in  milk  or 
cream  may  be  retarded  by  the  addition  of  various'  chemicals, 
such  as  borax,  formalin,  and  others.  They  are  substitutes 
for  cleanliness  and  refrigeration,  besides  being  undesirable 
constituents  of  an  article  of  food.  Their  use  in  milk  has  been, 
and  needs  to  be,  very  vigorously  opposed  by  pure  food  laws. 
The  campaign  against  the  use  of  milk  preservatives  has  been 
very  effective.  The  result  has  been  an  increase  in  the  use 
of  another  method  for  compensating  for  deficiencies  in  the 
care  of  milk,  that  is,  commercial  pasteurization.  Budde  has 
suggested  a  method  of  preserving  milk  by  the  addition  of 
hydrogen  peroxide,  which  is  ver}^  readily  removed  from  milk 
by  heating.  The  scheme  has  not  received  serious  consideration. 
The  matter  of  the  use  of  preservatives  and  their  detection,  is 
discussed  in  Chap.  XI.  The  changes  in  milk  constitute  a 
complex  biochemic  problem,  but  certain  of  the  more  common 
ones  may  be  discussed  in  a  systematic  manner. 

Lactic  acid  fermentation.  The  souring  of-  milk  is  the  mani- 
festation of  the  commonest  of  fermentative  changes  in  milk. 
As  a  result  of  bacterial  activities  the  lactose  is  transformed 
into  lactic  acid,  which  compound  is  responsible  for  the  char- 
acteristic flavor  and  curdling  of  soured  milk.  A  considerable 
number  of  bacteria  are  capable  of  inducing  the  change,  but 
it  has  been  shown  that  a  very  small  group  of  organisms  are 
ordinarily  found  in  milk  when  souring  is  well  advanced.  In 
fact,  one  of  these,  Bad.  lactis  acidi,  may  be  regarded  as 
the  typical  lactic  acid  organism.  It  has  been  found  in  nu- 
merous examinations  made  of  milk  from  widely  separated 
quarters  of  the  United  States.  Its  identity  with  the  lactic  acid 
organism  described  by  L,eichmann  in  Europe  has  been  estab- 
lished and  this  fact  adds  strength  to  the  view  that  it  may  be 
regarded  as  the  common  lactic  acid  organism.  This  organism 
has  been  classified  as  a  rod  form  (bacterium)  because  the  indi- 
vidual cells  are  usually  longer  than  broad.  It  forms  chains 
of  greater  or  less  length  and  in  bouillon  culture  sometimes 
appears  as  chains  of  undoubted  micrococci.  Streptococcus  lac- 
ticus  Kruse  is  another  widely  distributed  organism  observed 
to  predominate  in  souring  milk.  Some  writers  have  insisted 


LACTIC  ACID  FERMENTATION.  27 

upon  abandoning  the  use  of  the  name  Bad,  acidi  laciici  L,eich- 
mann  on  the  ground  of  the  identity  of  the  organism  with 
Streptococcus  lacticus  Kruse.  The  discussion  illustrates  the 
difficulties  of  bacterial  classification  and  has  certainly  empha- 
sized the  fact  of  the  common  occurrence  in  milk  of  strep- 
tococci and  other  forms  almost  indistinguishable  from  them. 
Members  of  the  B '.  laclis  aerogenes  and  B.  colt  communis  (37) 
groups  are  capable  of  causing  souring  of  milk,  but  require  a 
temperature  near  that  of  the  animal  body  in  order  to  flourish 
and  become  a  factor  in  the  souring  process.  The  fact  that  one 
species  of  lactic  acid  producing  organism  may  predominate  in 
milk  in  which  the  fermentation  is  well  advanced,  is  surely  an 
evidence  that  the  species  in  question  is  best  fitted  to  survive. 
In  the  earlier  stages  of  fermentation  a  greater  number  of  species 
participate,  but  gradually  succumb  in  the  competition  on 
account  of  intolerance  to  acid,  other  bacterial  products,  or 
other  environmental  conditions.  It  has  been  shown  that  a  cer- 
tain non-acid  producing  organism,  by  some  means,  creates  con- 
ditions more  favorable  to  Bact.  acidi  lactici,  and  contributes  to 
the  more  rapid  souring  of  milk  than  would  occur  without  its 
presence  (25,  26).  The  growth  of  lactic  acid  organisms  in 
souring  milk  is  not  unlimited,  for  eventually  their  multipli- 
cation is  checked  by  the  product  of  their  own  growth — lactic 
acid. 

The  lactic  acid  organism  owes  its  pre-eminence  in  milk  to  its 
thorough  adaptation  to  the  environment  in  competition  with 
other  organisms.  In  fresh  milk  it  forms  a  small  percentage  of 
the  bacteria  present.  At  10°C.  (50°F.)  it  multiplies  slowly, 
gaining  no  advantage  over  competitors,  but  at  20°C.  (68°F.) 
it  predominates.  At  this  latter  temperature  milk  is  curdled  in 
forty  hours. 

The  lactic  acid  fermentation  is  deleterious  in  the  sense  that 
the  result  of  its  progress  terminates  the  period  during  which 
milk  is  a  salable  food  product.  When  milk  for  domestic  pur- 
poses sours  sooner  than  usual,  the  blame  is  laid  upon  the  dealer. 
This  fermentation  produces  manifestations  in  the  taste  and  ap- 
pearance of  the  milk  easily  recognized  by  the  consumer  and 
in  the  popular  mind  is  an  index  of  the  keeping  quality  of  the 


CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

product.  Its  occurrence  naturally  furnishes  the  principal  com- 
mercial incentive,  and  almost  the  only  such  one  that  milk 
dealers  have,  to  exert  efforts  to  improve  the  quality  of  milk  as 
regards  bacterial  content. 

The  attitude  of  the  buttermakers  and  cheesemakers  towards 
the  lactic  acid  fermentation  is  quite  the  reverse.  The  forma- 
tion of  lactic  acid  is  as  yet  a  necessary  step  in  the  manufacture 
of  both  butter  and  cheese.  The  maintenance  of  temperature 
conditions  favoring  the  fermentation  is  an  important  detail  in 
the  manufacture  of  both  products. 

That  sour  milk  is,  or  the  organisms  causing  it  are,  harmful 
to  the  average  normal  adult  cannot  be  maintained.  On  the 
contrary,  soured  dairy  products  frequently  form  an  article  of 
diet,  as  for  example,  buttermilk  and  plain  sour  milk.  Metch- 
nikoff  has  laid  emphasis  upon  the  value  of  sour  milk  as  an 
article  of  diet  (28). 

The  importance  of  the  lactic  acid  fermentation  has  occas- 
ioned considerable  experimental  work  to  determine  the  source 
from  which  the  bacteria  commonly  gain  access  to  milk.  The 
existence  of  bacteria  within  the  udder  has  suggested  a  study 
of  those  organisms  with  reference  to  the  possible  presence  of 
that  one  among  them.  They  have  been  isolated  a  few  times 
from  cultures  made  direct  from  the  glandular  tissue  of  freshly 
slaughtered  animals.  Extensive  examinations  of  the  bacterial 
flora  of  milk  drawn  with  aseptic  precautions  have  shown  them 
in  such  few  instances  that  their  presence  in  those  particular 
samples  was  regarded  as  an  accidental  contamination  from 
sources  other  than  the  interior  of  the  udder.  For  instance,  in 
a  series  of  two  hundred  and  five  samples,  taken  from  seventy 
cows  during  several  days,  the  organism  was  found  in  only 
eight  instances  (7).  Examinations  of  the  stable  air  and  the 
dust  shaken  from  the  animal  during  milking  have  shown  the 
constant  presence  of  Bad.  acidi  lactici.  The  conclusion  follows, 
that  milk  is  contaminated  with  the  lactic  acid  organisms  while 
being  drawn,  and  that  the  interior  of  the  udder  is  of  no  im- 
portance as  a  source.  The  observations  made  did  not  include 
the  influence  of  dirty  utensils  containing  souring  milk,  which, 
of  course,  is  a  factor,  the  importance  of  which  is  obvious. 


PUTREFACTIVE  PROCESSES.  29 

Putrefactive  processes.  The  decomposition  changes  of  the 
casein  and  albumen  of  milk  by  bacterial  action  are  less  notice- 
able than  the  decomposition  of  milk  sugar,  but  more  important 
from  a  hygienic  point  of  view.  Such  alteration  of  nitrogenous 
compounds  is  designated  putrefaction,  and  in  the  process  the 
milk  assumes  an  alkaline  reaction.  Among  the  direct  products 
of  the  bacteria,  or  decomposition  products  of  nitrogenous  com- 
pounds produced  by  them,  are  some  that  produce  toxic  effects 
in  man.  The  changes  under  ordinary  conditions  are  not  such 
as  to  callthe  attention  of  the  consumer  to  the  condition,  as  in 
the  case  of  soured  milk. 

Organisms  causing  putrefaction.  As  in  the  case  of  the  lactic 
acid  fermentation,  a  great  number  of  species  are  capable  of 
inducing  putrefaction.  The  organisms  are  frequently  spore 
bearers,  and  when  cultivated  on  gelatin  usually  cause  lique- 
faction of  that  medium.  The  change  is  induced  by  enzymes 
elaborated  by  the  organisms  and  acting  thereafter  quite  inde- 
pendently of  them.  This  action  is  illustrated  in  gelatin  by 
the  area  of  liquefaction  surrounding  the  growth  of  the  organ- 
ism. In  milk  the  action  on  the  nitrogenous-  constituents  may 
or  may  not  be  preceded  by  a  curdling  of  the  milk  by  enzyme 
action.  Milk  poorly  cooled  in  hot  weather  will  sometimes 
curdle,  showing  a  weakly  acid  or  alkaline  reaction,  due  to 
enzyme  action.  The  group  of  organisms  of  which  Bacillus 
subtilis  is  the  type  is  a  common  representative  of  the .  putre- 
factive organisms. 

Antagonism  of  lactic  acid  fermentation.  The  active  progress 
of  putrefactive  changes  does  not  occur  under  conditions  favor- 
ing the  souring  of  milk,  for  the  rapid  multiplication  of  the 
lactic  acid  organisms  creates  conditions  unfavorable  for  putre- 
faction (5).  In  this  sense,  souring  may  be  considered  as  a 
beneficent  process,  protecting  milk  against  a  worse  decomposi- 
tion. 

Conditions  controlling  putrefaction.  Putrefactive  organisms 
are  able  to  multiply  at  temperatures  somewhat  below  20°  C. 
more  rapidly  than  the  lactic  acid  organisms.  Hence,  milk 
kept  at  low  temperatures  is  more  apt  to  undergo  putrefaction 
than  souring.  The  point  should  be  made  that  at  such  tempera- 


30  CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

tures  putrefaction  goes  on  slowly,  so  that  this  circumstance  is 
of  no  practical  importance  in  the  care  of  milk  as  customarily 
kept  for  consumption.  A  very  old  milk,  however,  even  though 
it  has  been  kept  at  12°C.  and  not  sour,  may  not  be  free  from 
the  products  of  putrefaction. 

Source  of  putrefactive  organisms.  The  dust  of  stable  air, 
and  particularly  the  filth  dropping  into  the  milk  pail  from  the 
udder  and  flanks  of  the  cow,  certainly  contribute  liberally  to  in- 
fection by  putrefactive  organisms.  Poorly  cleansed  milk  uten- 
sils and  polluted  water  deserve  mention.  In  fresh  milk  these 
organisms  greatly  outnumber  the  lactic  acid  organisms. 

Toxic  milk.  There  are  011  record  a  few  cases  of  poisoning 
believed  to  have  been  due  to  the  elaboration  of  toxic  substances 
by  bacteria  in  milk.  Very  little  is  known  about  the  topic. 
Kastle  (21)  has  made  a  summary  of  the  subject  and  has  col- 
lected a  bibliography. 

Ropy  milk.  None  of  the  faults  of  milk  arouse  the  distrust 
of  the  consumer  more  than  the  viscid  condition  of  milk  and 
cream,  popularly  designated  "ropy."  The  widespread  abhor- 
rence of  milk  in  this  condition  is  induced  by  the  belief  that 
it  is  the  product  of  a  diseased  udder.  The  false  inference 
is  encouraged  by  the  fact  that  dairymen  sometimes  refer  to  the 
milk  of  an  inflamed  udder  as  "ropy"  or  "stringy."  There 
is  no  relation  between  the  two  and  no  real  confusion  beyond 
that  induced  by  the  double  significance  of  the  word  ropy. 
There  is  no  ground  for  attributing  a  harmful  result  from  the 
consumption  of  the  ropy  milk  delivered  to  customers,  but  the 
occurrence  of  the  trouble  menaces  the  success  of  a  milk  route 
by  occasioning  loss  of  custom. 

The  viscid  condition  appears  not  sooner  than  twelve  hours, 
but  sometimes  as  late  as  thirty  hours,  after  milking.  Further- 
more, it  is  most  readily  observed  in  milk  that  has  stood  undis- 
turbed for  several  hours,  during  which  period  the  cream  has 
risen.  These  conditions  give  the  false  impression  that  the 
trouble  is  only  associated  with  cream,  while,  in  fact,  skim 
milk  is  just  as  susceptible  to  the  trouble.  The  consistency  of 
cream  does,  however,  accentuate  the  viscosity.  Fig.  5  shows 
the  behavior  of  ropy  cream  when  lifted  with  a  fork. 


ROPY  MILK. 


31 


Cause. of  ropy  milk.  The  condition  is  brought  about  by  the 
presence  of  Bacillus  lactis  viscosus,  described  first  by  Adametz 
(l).  The  individual  bacteria  possess  enveloping  masses  of 

slimy  viscid  material, 
which  impart  a  similar 
characteristic  to  the 
milk  when  they  are 
present  in  sufficient 
numbers.  Fig.  6 
shows  the  ropy  milk 
organisms.  The  cap- 
sules of  viscid  sub- 
stance are  represented 
by  white  areas  sur- 
rounding each  cell. 

Many  organisms  ca- 
pable of  inducing  vis- 
cosity when  grown  in 
milk,    under    various 
conditions,  have  been 
described .     Advances 
in  methods  of  identi- 
fying bacteria  make  it 
impossible  to  say  how 
many  of  these    organisms    are 
really  identical.     The  more  re- 
cent studies  of  the  occurrence 
of  ropy  milk  in  dairies  in  North 
America  and  Europe,   point  to 
the    conclusion    that    B.    lactis 
viscosus  is  very  largely  the  cause 
of  the  trouble.     The  ropy  milk 
organisms  isolated  by  the  writer 
have  always  been  of  this  species 
(42) .    Harrison  has  found  some 
different  species  (16). 


Fig.  5.     Ropy  cream  lifted  with  a  fork 


Fig.  6.     Bacillus  lactis  viscosus, 
from  a  milk  culture  (42). 


32  CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

Biological  characteristics  of  B.  lactis  viscosits.  The  organism 
has  been  isolated  from  water,  which  is  considered  its  natural 
habitat.  Growth  is  fairly  luxuriant  at  15°  C.  (59°  F.),  best 
at  25°  C.  (77°  F.)  and  very  slight  at  37°  C.  (98°  F.).  How- 
ever, 8°  C.  (46°  F.)  is  not  low  enough  to  inhibit  growth.  The 
organisms  multiply  rapidly  enough  in  ice  water  to  induce  vis- 
cosity in  milk  kept  in  cans  in  ice  water.  That  is,  this  organ- 
ism forms  an  exception  to  the  rule  that  care  in  cooling  milk 
inhibits  the  multiplication  of  bacteria.  At  low  temperatures 
the  ropy  milk  organisms  have  a  comparatively  clear  field  for 
growth,  free  from  serious  competition  with  the  lactic  acid  or- 
ganisms. At  higher  temperatures,  such  is  not  the  case.  B '. 
lactis  visco'sus  will  grow  only  in  the  presence  of  air,  which  ac- 
counts for  the  appearance  of  viscosity  first  on  the  top  of  milk. 
This  biological  peculiarity  is  doubtless  the  reason  that  ropy 
milk  is  never,  or  rarely,  seen  in  bottled  milk.  The  organism 
does  not  form  spores,  and  is  killed  in  culture  by  exposure  to 
58°  C.  (136°  F.)  for  ten  minutes  (16,  41). 

Sources  of  contamination  of  milk.  The  fact  that  B '..  lactis  vis- 
cosus  grows  with  great  difficulty  at  blood  heat,  effectually  dis- 
poses of  any  suspicion  that  ropy  milk  is  the  result  of  disease 
in  the  cow.  Water  must  be  regarded  as  the  original  source  of 
trouble,  but  it  may  by  no  means  be  the  immediate  one.  The 
cow  may,  sometimes,  carry  the  organisms  on  the  hairy  coat, 
from  water  to  the  milk.  Several  observers  have  isolated  ropy 
milk  organisms  from  stable  air.  When  ropy  milk  is  causing 
trouble,  the  organisms  are  found  with  great  frequency  in  sam- 
ples taken  from  the  floor  dust  of  milk  rooms.  The  practice  of 
cooling  cans  of  milk  nearly  immersed  in  a  vat  of  ice  water  af- 
fords, in  the  milky  water,  favorable  conditions  for  the  multi- 
plication of  the  organisms  and  for  the  contamination  of  the 
milk  by  them.  The  spattering  of  water,  incident  to  moving 
cans  or  adding  ice,  gives  opportunity  for  the  contamination  of 
the  milk.  The  corrugated  milk  cooler,  containing  water  in 
circulation,  may  have  a  leak,  giving  opportunity  for  direct 
contamination  from  water.  The  practice  of  merely  rinsing 
utensils  at  night  and  using  them  in  the  morning  without  scald- 
ing, gives  another  opportunity  for  bringing  water  into  contact 


ROPY  MILK.  33 

with  the  milk.  Unclean  utensils  constitute  the  greatest  factor 
in  the  contamination  of  milk.  The  wire  mesh  strainer,  parti- 
ally clogged  with  filth,  may  be  the  only  visible  evidence  of 
carelessness.  Bacteriological  examination  of  the  supposedly 
clean  utensils  will  reveal  the  presence  of  ropy  milk  organisms 
in  a  large  percentage  of  examinations.  This  is  most  readily 
done  by  pouring  separate  samples  of  sterilized  milk  into  the 
various  suspected  utensils  and  then  immediately  out  again. 
These  samples  kept  at  a  low  temperature  for  several  days  will 
become  viscid  if  they  have  been  in  contact  with  the  bacteria 
of  ropy  milk.  Attention  to  the  technic  of  washing  utensils 
will  reveal  the  fact  that  the  scalding  is  not  carried  out  in  accord- 
dance  with  the  bacteriological  requirements  governing  the  prac- 
tice. Carelessness  in  this  regard  is  by  no  means  limited  to 
farmers  with  poor  scalding  equipment.  It  is  just  as  frequently 
the  result  of  too  hasty  steaming  of  cans  by  employees  in  large 
city  concerns,  who  misuse  the  abundant  facilities  for  scalding 
at  their  disposal.  Gross  neglect,  therefore,  permits  the  ropy 
milk  organisms  to  exist  in  milk  utensils  from  day  to  day,  to  con- 
taminate each  succeeding  lot  of  milk.  Under  such  conditions 
the  mill^  strainer,  designed  to  improve  the  quality  of  milk, 
becomes  a  potent  factor  in  its  deterioration. 

Means  of  corn-bating  ropy  milk.  The  control  of  this  milk 
fault  is  a  comparatively  simple  matter  when  bacteriological 
principles  are  borne  in  mind.  In  most  cases  the  trouble  may 
be  abated  by  instituting  the  continued  practice  of  a  thorough 
scalding  of  every  utensil  with  which  milk  comes  in  contact. 
In  the  absence  of  steam,  immersion  in  boiling  water  for  three 
to  five  minutes  will  serve  the  purpose.  Milk  cans  too  large 
for  immersion  in  the  vessel  at  hand  may  be  filled  with  boiling 
water  and  should  be  left  filled  for  five  minutes.  As  a  pre- 
caution against  dust  contamination,  pails  and  cans,  after  clean- 
ing, should  be  stood  bottom  side  up.  Strainers,  coolers,  etc., 
should  likewise  be  protected  in  some  manner.  In  most  cases 
the  dirty  wire  strainers  may  be  replaced  by  cheesecloth  strain- 
ers. The  sources  of  contamination  from  water  are  easily 
remedied.  The  location  of  the  source  from  which  contamin- 
ation is  derived  may  be  determined  by  taking  samples  of  milk 


34  CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

at  various  stages  in  the  handling,  and  watching  for  the  appear- 
ance of  ropiness  after  the  milk  has  stood  a  day  in  a  cool  place. 
Frequently  it  will  be  found  that  the  milk  as  it  comes  from  the 
stable  is  normal  and  that  the  source  of  contamination  is  in  the 
milk  room.  If  such  is  not  the  case,  the  dampening  of  the 
udders  of  the  cows,  before  milking,  will  be  necessary  (41,  42). 

Germicidal  activity,  When  samples  of  freshly  drawn  milk 
are  examined  at  frequent  intervals  for  numbers  of  bacteria,  the 
fact  becomes  evident  that  the  total  numbers  do  not  immediately 
begin  to  increase.  The  numbers  may  decrease  or  remain  sta- 
tionary for  a  period  before  the  increase  of  bacteria  begins. 
Immediate  increase  of  total  numbers  is  distinctly  the  exception. 
The  phenomenon  varies  in  degree  in  the  milk  of  individual 
cows  (20). 

Kunze  (22)  determined  the  number  of  bacteria  in  milk  when 
freshly  drawn,  after  thorough  cooling,  after  sixteen  hours  at 
6-8°C.  and  after  forty  hours  at  6-8 °C.  He  averaged  the  results 
of  35  samples  collected  at  periods  covering  a  whole  year.  The 
freshly  drawn  milk  was  very  clean,  averaging  only  about  four 
hundred  colonies  per  cc.  Thorough  cooling  alone  reduced  the 
original  count  by  11.4%  .  After  sixteen  hours  at  6-8° C.  it  was 
reduced  by  16.8%.  At  forty  hours  the  count  was  33.09%  of 
the  original,  a  reduction  of  21.69%  from  the  count  taken  just 
after  cooling. 

The  length  of  the  period  of  decline,  in  any  case,  is  governed 
by  the  temperature  at  which  the  milk  is  kept.  For  instance, 
at  37°C.  (98°F.)  the  period  las'ts  about  three  hours  ;  at  21°C. 
(70°F.),  three  to  twelve  hours  ;*  at  13°C.  (55°F.),  about  twenty- 
four  hours;  at  4°C.  (40°F.),  forty-eight  hours;  at  1°C.  (34°F.), 
six  to  eight  days. 

The  temperature  governs  the  extent  of  decrease.  At  70°F. 
the  decrease  is  marked,  frequently  50%  or  more  in  market 
milk.  At  55°F.  it  is  less  marked,  and  at  40°F.  still  less. 
These  observations  are  presented  in  a  graphic  way  in  Fig.  7. 
The  chart  (Fig.  7)  shows  the  changes  in  the  number  of  bac- 
teria in  three  portions  of  the  same  original  sample  of  milk, 
kept  at  different  temperatures.  The  sample  was  drawn  from 
the  cow  with  the  strictest  aseptic  precautions. 


36  CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

The  germicidal  action  is  observed  in  samples  drawn  so  care- 
fully that  none  but  the  micrococci  from  the  interior  of  the 
udder  are  present,  as  well  as  in  samples  of  highly  contaminated 
market  milk.  The  fact  that  the  greater  decrease  in  milk  con- 
taining only  udder  micrococci  occurs  at  70°F.,  rather  than  at 
40°F.,  is  of  interest.  The  explanation  has  been  advanced  very 
recently  (22)  that  these  organisms  die  off  in  refrigerated  milk, 
because  the  temperature  is  so  different  from  that  to  which  they 
are  accustomed.  The  theory  does  not  harmonize  all  the  facts 
observed  in  connection  with  the  phenomenon. 

The  germicidal  action  of  milk  is  destroyed  by  heat,  being 
stopped  completely  by  176°F.  for  forty  minutes.  Milk  heated 
to  the  same  temperature  for  twenty  minutes  shows  no  decrease 
of  the  milk  bacteria  freshly  implanted  in  it,  and  no  increase  for 
several  hours.  Similarly  149°F.,  for  forty  minutes,  resulted 
in  the  restraint  of  growth  for  nine  hours.  Exposure  to  131°F. 
for  thirty  minutes,  or  140°F.  for  twenty  minutes,  has  been 
sho\vn  to  destroy  the  germicidal  activity  of  milk  against  B. 
lactis  aerogenes,  but  had  no  influence  upon  its  action  on  B. 
typhosus. 

Fresh  milk,  drawn  with  aseptic  precautions  and  planted  with 
pure  cultures  of  various  pathogenic  organisms,  has  shown  a 
decrease  in  colonies  in  plate  cultures,  while  sterilized  milk  has 
shown  an  immediate  increase.  Among  the  organisms  tested 
are  the  germs  of  typhoid,  cholera,  diphtheria,  dysentery  and 
B.  lactis  aerogenes,  a  common  lactic  acid  producer  (35). 

A  given  sample  of  milk  may  show  a  selective  specific  action 
with  reference  to  its  restraining  action  on  different  organisms. 
In  a  given  sample  one  organism  may  immediately  multiply, 
while  another  may  not.  It  has  been  shown  that  the  common 
lactic  acid  organisms  in  market  milk  usually  increase  from  the 
beginning  even  when  other  forms  are  disappearing  so  rapidly 
that  the  total  numbers  are  decreasing.  It  has  been  suggested 
that  the  leucocytes  in  milk  destroy  the  bacteria  by  phagocy- 
tosis. This  does  occur  to  some  extent,  but  it  has  been  shown 
that  it  is  not  responsible  for  the  great  changes  observed  (35). 

Some  recent  studies  go  to  show  .that  the  decrease  is  more 
apparent  than  real.  Agglutination  occurs,  and,  with  the  mod- 


GKRMICIDAL  ACTIVITY.  37 

erate- agitation  of  making  dilutions  for  plate  cultures,*  these 
clumps  would  remain  undisturbed  (35).  Thus,  the  number 
of  colonies  on  the  medium  would  decrease,  while  plates  made 
from  milk  that  had  been  most  violently  agitated  would  show 
an  increase.  This  gives  a  reason  for  the  discrepancies  between 
the  results  of  various  workers,  and  goes  a  long  way  toward 
explaining  the  phenomenon. 

It  has  been  generally  assumed  by  writers  on  the  subject, 
that  the  decrease  in  numbers  of  colonies  on  plates  indicated 
the  death  of  the  organisms  concerned.  Most  writers  consid- 
ered this  due  to  some  germicidal  property  of  milk.  It  has  been 
suggested  that  many  organisms  die  off  in  milk  because  they 
find  there  an  environment  wholly  unsuited  to  them.  This  is 
undoubtedly  true  to  some  extent,  but  hardly  accounts  for  some 
of  the  latest  observations  published.  Agglutination  seems  to 
account  for  a  large  part  of  the  apparent  decrease  in  numbers. 
Even  making  allowance  for  this,  it  is  evident  that  raw  milk 
exerts  a  restraining  influence  on  the  multiplication  of  bacteria 
as  compared  with  heated  milk.  In  the  light  of  this  view,  the 
phenomenon  might  be  described  as  similar  to  the  action  of  a 
weak  antiseptic  (35). 

The  evidence  at  hand  does  not  warrant  recommending  a 
change  in  the  general  practice  of  rapid  cooling  of  milk.  That 
is,  it  has  not  been  proven  that  delay  in  cooling  would  improve 
the  keeping  quality.  It  is  certain,  though,  that  the  phenom- 
enon should  be  taken  into  consideration  in  judging  the  success 
of  efforts  to  secure  germ-free  milk.  The  length  of  time  after 
milking,  and  the  temperature,  should  be  taken  into  consider- 
ation when  various  bacterial  determinations  are  compared,  and 
submitted  as  evidence  of  success  in  aseptic  milking.  For 
instance,  the  work  reported  in  Ref.  69,  Chap.  I,  was  appar- 
ently done  without  recognition  of  this  important  factor. 


*  The  common  method  of  counting  bacteria  is  described  in  Chap.  VIII. 


38  CHANGES  IN  MILK  CAUSED  BY  BACTERIA. 

REFERENCES. 

1.  ADAMETZ.      Untersuchungen  iiber  Bacillus  lactis    viscosus,  einen 
weit  verbreiteten  niilchwirtschaftlichen  Schadling.    Landw.  Jahrb.,  Ber- 
lin, 1891,  S.  175. 

2.  ADAMETZ.    Centbl.  Bakt. ,  etc.,  2.  Abt.,  Bd.  VI,  1900,  No.  12,  S.  406. 

3.  AI.VORD  and   PEARSON.     The  milk  supply  of  two  hundred  cities 
and  towns.     Bui.  No.  46,  Bur.  Anim.  Ind.,  V.  S.  Dept.  Agr.,  1903. 

4.  BERLINER.    Milk  during  transportation.    Cir.  Xo.  114,  Bur.  Anim. 
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5.  BOUSKA.     Studien  iiber  den  Antagonismus  zwdschen  Milchsaurefer- 
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6.  BURR.     Investigations  on  the  sources  of  the  acid  organisms  con- 
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Sta.,  Storrs,  Conn.,  1900,  p.  66. 

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9.  CONN.     The  relation  of  temperature  to  the  keeping  quality  of  milk. 
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p.  91. 

13.  CONN  and  STOCKING.     Studies  concerning  the  so-called  germi- 
cidal  action  of  milk.     Rev.  Gen.  Lait,  Vol.  II,  Nos.  12  and  13. 

14.  DOANE.     Economical  methods  for  improving  the  keeping  quali- 
ties of  milk.     Bui.  No.  88,  Maryland  Agr.  Exp.  Sta.,  College  Park, 
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15.  DOANE.     The  milk  supply  of  twenty-nine  southern  cities.     Bui. 
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REFERENCES.  39 

18.  HEINEMANN.     The  kinds  of  lactic  acid  produced   by  lactic  acid 
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20.  HUNZIKKR.     Investigations   concerning  the  germicidal  action  in 
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23.  IvOHNis.      Versuch  einer  Gruppierung  der  Milchsaurebakterien. 
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27.  MARSHALL  and  FARRAND.     Bacterial  associations  in  the  souring 
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29.  MOORE.     Bacteria  in  milk.     Circular  published  by  the  Commis- 
sioner of  Agriculture  of  New  York,  Albany,  1902. 

30.  MiJLLER.     Vergleichende  Untersuchungen  iiber  Milchsaurebak- 
terien (des  Typus  giintheri)  verschiedener  Herkunft,  nebst  Beitrag  zur 
Frage  der  Stellung  dieser  Organismen  zu  den  typischen  Streptokokken. 
Centbl.  Bakt.,  etc.,  2.  Abt.,  Bd.  XVII,  S.  468. 

31.  PARK.     The  great  bacterial   contamination  of  the  milk  of  cities, 
can  it  be  lessened  by  the  action  of  health  authorities?     New  York  Uni- 
versity, Bui.  Med.  Sci.,  Vol.  I,  1901,  p.  71. 

32.  PENNINGTON.     Bacterial  growth  and   chemical  changes  in  milk 
kept  at  low  temperatures.    Jour.  Biol.  Chem.,  Vol.  IV,  1908,  Nos.  4  and 
5,  p.  353. 

33.  REVIS.     The  acid  coagulation  of  milk.   Jour.  Hyg.,  Vol.  7,  p.  216. 

34.  ROSENAU.     The  number  of  bacteria  in  market  milk  and  the  value 
of  bacterial  counts.     Bui.  No.  41,  U.  S.  Pub.  Health  and  Mar.  Hosp. 
Sen>.,  Washington,  D.  C.,  1908,  p.  421. 


40  CHANGES  IX  MILK  CAUSED  BY  BACTERIA. 

35.  ROSENAU  and  McCov.     The  gerniicidal  property  of  milk.     Bui. 
No.  41,  Hyg.  Lab.,  L\  S.  Pub.  Health  and  Mar.  Hosp.  Sen>.,  Washing- 
ton, D.  C.,  p.  449. 

36.  RUSSELL.     Outlines  of  dairy  bacteriology.     Madison,  Wis.:  H.  Iv. 
Russell,  1899. 

37.  SAVAGE.     The  coagulation  of    milk  by  Bacillus   coli  communis. 
Jour.  Path,  and  Bad.,  Vol.  10,  1908,  p.  90. 

38.  STEWART  and  ATWOOD.     Bacteria  in  milk  and  artificial  refriger- 
ation for  dairymen.     Bui.  No.  Ill,  West  Virginia  I  'nil'.  Agr.  Exp.  Sta., 
Morgantown,  W.  Va.,  1908. 

39.  ST.  JOHN  and  PENNINGTON.     The  relative  rate  of  growth  of  milk 
bacteria  in  raw  and  pasteurized  clean  milk.    Jour.  Infect.  J)is.,  Vol.  IV, 
1907,  No.  4,  p.  647. 

40.  STOCKING.     The  so-called  germicidal  property  of  milk.    Bui.  No. 
37,  Storrs  Agr.  Exp.  Sta.,  Storrs,  Conn. 

41.  WARD.     Ropiness  in   milk  and  cream.      Bui.  No.  165,  Cornell 
Univ.  Agr.  Exp.  Sta.,  Ithaca,  N.  Y.,  1899. 

42.  WARD.     Further  observations  upon  ropiness  in  milk  and  cream. 
Bui.  No.  195,  Cornell  ('nil'.  Agr.  Exp.  Sta.,  Ithaca,  N.  Y.,  1901. 

43.  WHITAKER.     The  milk  supply  of  Boston  and  other  New  England 
cities.     Bui.  No.  20,  Bur.  Anim.  /m/.,  (\S.  Dept.  Agr.,  Washington, 
D.  C.,  1898. 

44.  WHITAKER.     The  milk  supply  of  Boston,  New  York  and  Phila- 
delphia.    Bui.  No.  81,  Bur.  Anim.  hid.,  ( '.  S.  Dept.  Agr.,  Washington, 
D.  C.,  1905. 

45.  WOLF.     Zur  Kenntnis  der  Veranderungen  in  der  Bakterienflora 
der    frischen    Milch   wahrend    der    sogennanten     Inkubatioiisstadiums. 
Centbl.  Bakt.,  etc.,  2.  Abt.,  Bd.  XX,  1908,  No.  18,  S.  545. 


CHAPTER  III. 


EPIDEMIC  DISEASES  TRANSMITTED  BY  MILK. 


Transmission  of  diseases  of  man  by  milk.  Milk  traffic  as 
now  constituted,  offers  a  particularly  favorable  channel  for 
the  transmission  of  certain  diseases  of  man.  The  close  con- 
tact of  human  beings  incident  to  the  handling  of  milk  at  the 
producing  dairies,  coupled  with  the  general  lack  of  observance 
of  aseptic  precautions  in  the  work,  offer  frequent  opportunities 
for  contamination  of  the  product.  Milk  offers  conditions  that 
are  not  unfavorable  to  the  bacteria  of  typhoid  fever  and  diph- 
theria, and  they  may  even  multiply  therein.  The  unrecog- 
nized virus  of  scarlet  fever  likewise  finds  conditions  favorable. 

The  wide  use  of  milk  among  households  gives  opportunity 
for  very  broad  distribution  of  infection  through  milk.  The 
output  of  a  dairy  may  not  go  to  the  same  consumers  from  day 
to  day,  so  the  field  for  the  possible  infliction  of  damage  by  a 
dairy  is  yet  more  widened. 

Character  of  milk-borne  epidemics*  The  large  well-marked 
epidemics  borne  by  milk  are  characterized  by  the  almost  sim- 
ultaneous appearance  of  cases  among  patrons  of  the  milk  route. 
Variations  occur,  due  to  individual  idiosyncrasy  with  respect 
to  the  incubation  period  of  the  disease.  As  likely  as  not  the 
primary  cases,  attributable  to  the  milk,  will  cease  to  occur  as 
suddenly  as  they  began.  L,ater,  there  will  be  observed  second- 
ary cases  among  members  of  the  same  or  different  households. 
The  causative  relation  of  milk  stands  out  most  clearly  in  out- 
breaks derived  entirely  from  milk,  and  not  complicated  by  the 
concurrent  presence  of  the  disease  due  to  other  quite  different 
channels  of  dissemination  (18). 

Very  thorough  study  of  reported  cases  of  typhoid  and  diph- 
theria in  a  city,  with  reference  to  the  milk  supply,  have  led  to 
the  conclusion  that  milk  is  responsible  for  many  isolated  cases 


42  EPIDEMIC  DISEASES  TRANSMITTED  BY  MILK. 

of  these  diseases.     That  is  to  say,  these  diseases  may  occur  as 
a  result  of  contaminated  milk,  and  escape  notice  ordinarily. 

Typhoid  fever.  Typhoid  is  the  most  common  of  the  epi- 
demic type  of  infectious  diseases.  Little  by  little  it  is  be- 
ginning to  be  recognized  that  milk  stands  next  to  water  as  a 
means  for  spreading  infection.  In  this  connection  it  is  inter- 
esting to  note  that  typhoid  fever  is  relatively  more  prevalent 
in  rural  districts  than  in  cities.  Fulton  has  collected  the  fol- 
lowing figures,  quoted  by  Whipple  (38)  : 

TABLE  II. 
TYPHOID  FEVER  IN  URBAN  AND  RURAL  POPULATIONS. 


Av.  %  of        Av. 
rural      typhoid 
popula-     rate  per 
tion.          1000. 

5  states  with  urban  population  of  more  than  60  %  of  total 

30  .... 

....  25 

6     " 

of  40  to  60%  of  total.... 

49  ... 

....  42 

7     " 

of  30  fo  40  %  of  total  .... 

67  .... 

....  38 

8     " 

of  20  to  30%  of  total  

75  .... 

...  46 

12     " 

of  10  to  20%  of  total  

87  .... 

....  62 

12     " 

of    0  to  10%  of  total  

95  .:.. 

....  67 

Investigations  in  the  District  of  Columbia.  During  the  past 
two  years  very  thorough  investigations  have  been  made  of  the 
source  of  infection  of  the  typhoid  fever  cases  occurring  in  the 
District  of  Columbia  during  the  months  May  to  October  in- 
clusive. The  work  was  instituted  in  consequence  of  the  obser- 
vation that  the  installation  of  a  satisfactory  system  of  water 
filtration  did  not  produce  a  satisfactory  lowering  of  the  typhoid 
fever  rate.  In  1906  it  was  possible  to  definitely  assign  a  source 
of  infection  in  the  case  of  only  18.6%  of  all  reported  cases 
believed  to  have  originated  in  the  District'.  Among  these, 
11.3%  of  all  were  attributed  to  milk  and  7.3%  to  contact. 
That  is,  60.8%  of  all  traceable  cases  were  milk-borne.  In  1907, 
the  figures  were  :  traceable  to  milk,  9. 18% ;  to  contact,  19.50% ; 
total  accounted  for,  28.68%  .  In  that  year  32c/c  of  all  traceable 
cases  were  attributed  to  milk. 


TYPHOID  FEVER.  43 

The  careful  study  of  the  cases  of  typhoid  fever  in  the  Dis- 
trict of  Columbia  with  reference  to  the  source  of  the  milk,  has 
made  it  possible  to  compile  figures  showing  the  amount  of  that 
disease  traceable  to  each  dealer.  The  results  appearing  in  the 
reports  (28,  29)  on  the  work  are  rearranged  in  the  appended 
table. 

In  1906  definite  outbreaks  of  typhoid  fever  were  attributed 
to  dairies  No.  4  and  No.  13.  Note  the  difference  in  the  rate 
of  typhoid  attributed  to  these  dairies  in  1907,  when  no  out- 
breaks occurred  among  their  customers.  In  1907,  dairy  No. 
163  was  the  source  of  an  outbreak. 

Dairy  No.  10  makes-a  very  fine  showing  during  both  seasons, 
attributed  to  the  fact  that  efficient  methods  for  sterilizing  the 
bottles  and  for  pasteurizing  the  milk  were  used.  The  good 
showing  of  dairy  No.  17,  in  1908,  may  be  attributed  to  the 
fact  that  an  efficient  method  of  sterilizing  bottles  was  used  and 
to  the  fact  that  a  portion  of  the  milk  was  derived  from  a  special 
dairy.  Suspected  outbreaks  were  attributed  to  dairies  Nos.  8, 
44  and  46  in  1907. 

The  work  on  typhoid  fever  in  the  District  of  Columbia  led 
Rosenau,  Lumsden  and  Kastle  to  the  conclusion  that  infected 
milk  is  one  of  the  important  known  factors  in  the  spread  of  the 
disease  there.  This  view  concerning  the  relation  of  milk  to 
the  spread  of  the  disease  has  been  expressed  by  others. 

Importance  of  milk  as  a  carrier.  Whipple  writes,  on  page 
132  of  his  book  (38): 

"  In  a  general  sort  of  way  it  may  be  said  that  in  the  cities  of  the  United 
States,  at  the  present  time,  about  40  per  cent,  of  the  typhoid  fever  is  due 
to  water,  25  per  cent,  to  milk,  30  per  cent,  to  ordinary  contagion  (includ- 
ing fly  transmission),  and  only  about  5  per  cent,  to  all  other  causes." 

Neufeld  (22)  considers  that  milk  is  next  in  importance  to 
water  as  a  means  for  transmitting  typhoid  fever.  Trask  (32) 
has  collected  data  concerning  317  milk-borne  typhoid  fever 
epidemics.  Harrington  (13)  states  that  during  two  years  the 
Massachusetts  State  Board  of  Health  investigated  18  local  epi- 
demics of  typhoid  fever.  Of  these,  14  were  milk-borne,  3  due 
to  water,  and  1  unexplained. ,  The  importance  of  milk  in  con- 
nection with  typhoid  has  till  lately  been  underestimated. 


TABLE   III. 


TYPHOID  FEVER  IN  THE  DISTRICT  OF   COLUMBIA   WITH  REFER- 
ENCE TO  THE  MILK  SUPPLY. 


May  to  October  inclusive . 
1906  1907 


Dairy 

No. 

No. 
Cases. 

Gallons  of 
Milk  vSold. 

No.  Cases 
per 
100,  000  gals. 
Milk  Sold. 

No. 
Cases. 

Gallons  of 
Milk  Sold. 

No.  Cases 
per 
100,  000  gals. 
Milk  Sold. 

Dairy 
No. 

1 

26 

142,986 

18.2 

19 

268,724 

7.1 

1 

2 

29 

134,911 

21.5 

50 

214,030 

23.4 

2 

3 

20 

119,889 

16.6 

11 

154,963 

7.1 

3 

4 

54 

102,867 

52.5 

32 

148,352 

21.6 

4 

5 

17 

77,098 

22.0 

10 

137,516 

7.2 

5 

6 

17 

71,690 

23.7 

20 

135,044 

14.8 

6 

7 

25 

71,350 

35.0 

16 

117,365 

13.6 

7 

8 

23 

62,903 

36.6 

22 

128,800 

17.1 

8 

9 

18 

51,115 

35.2 

9 

100,800 

8.9 

9 

10 

3 

44,496 

6.7 

8 

147,107 

5.4 

10 

11 

8 

43,800 

18.2 

7 

85,558 

8.2 

11 

12 

5 

39,286 

12.7 

10 

89,240 

11.2 

12 

13 

41 

35,995 

113.9 

6 

92,602 

6.5 

13 

14 

7 

31,984 

21.9 

4 

14 

15 

2 

31,542 

6.3 

5 

15 

16 

4 

29,247 

13.7 

4 

49,395 

8.1 

16 

17 

5 

27,247 

18.4 

2 

38,637 

5.2 

17 

18 

7 

24,829 

28.2 

2 

42,540 

4.7 

18 

19 

9 

22,005 

40.9 

19 

20 

4 

14,145 

28.3 

20 

21 

1 

13,909 

7.2 

- 

21 

22 

1 

12,845 

7.8 

22 

23 

3 

11,617 

25.8 

23 

24 

3 

11,617 

25.8 

24 

25 

4 

11,304 

35.4 

25 

26 

1 

11,187 

8.9 

26 

27 

0 

11,070 

0.0 

27 

28 

3 

10,836 

27.8 

28 

29 

— 



29 

30 

4 

9,697 

41.2 

30 

31 

4 

9,328 

42.9 

31 

32 

1 

8,320 

12.0 

32 

33 

1 

7,855 

12.8 

33 

34 

1 

7,723 

12.9 

34 

35 

4 

6,028 

66.4 

35 

36 

4 

5,225 

76.5 

36 

37 

1 

3,872 

25.8 

37 

38 

1 

3,182 

31.4 

38 

39 

1 

3,028 

33.0 

39 

40 

1 

2,168 

46.1 

40 

41 

0 

1,353 

0.0 

41 

10 

37,440 

26.7 

44 

18 

61,399 

29.3 

46 

NOTE  :  These  ratios  calculated   for  the 
months  of  July,  Aug.,  Sept  ,  and  Oct.  only. 

31 

10,955 

282.9 

163 

SOURCES  OF  THE  CONTAMINATION  OF  MILK.  45 

Sources  of  the  contamination  of  milk.  The  means  by  which 
typhoid  fever  bacilli  are  disseminated  by  the  individual  offer 
frequent  opportunity  for  the  infection  of  milk.  The  typhoid 
patient  is  believed  by  some  to  disseminate  the  disease  during 
the  incubation  period  and  early  stages  of  the  disease.  Certain 
it  is  that  patients,  long  before  taking  to  bed,  disseminate  ba- 
cilli through  the  urine  and  feces.  This  is  equally  true  of  walk- 
ing cases  that  never  take  to  bed.  The  danger  is  augmented 
by  the  fact  that  diagnosis  may  be  delayed  until  the  second  or 
third  week,  and  in  the  mild  cases  no  diagnosis  is  made,  and 
thus  no  warning  is  given. 

The  patient  in  bed  is  a  menace  through  the  careless  disposal 
of  excreta.  Thus,  infection  may  be  disseminated  through  the 
nurse,  by  flies  when  allowed  access  to  discharges  on  the  ground 
or  in  open  vaults,  and  by  the  contamination  of  the  well  or 
stream.  All  these  factors  may  play  a  part  in  milk  infection 
on  a  dairy  farm. 

The  convalescent  may  return  to  work  while  yet  dissemin- 
ating infection.  A  considerable  number  of  those  recovering 
from  typhoid  for  years  afterwards  continue  to  disseminate 
infection.  Such  cases  or  others  harboring  bacilli,  with  no 
previous  history  of  typhoid  fever,  are  called  bacilli  carriers, 
and  are  believed  to  be  significant  factors  in  the  spread  of  the 
disease  (25).  Adequate  means  for  protecting  the  public  from 
this  source  of  danger  have  not  yet  been  put  into  general  prac- 
tice. 

In  the  dairy  there  are  certain  practices  that  facilitate  the 
infection  of  milk.  The  failure  to  wash  the  hands  before  milk- 
ing and  the  common  practice  of  wetting  the  hands  with  milk 
are  particularly  dangerous.  As  likely  as  not  the  milker  may 
be  acting  as  nurse  in  the  sick  room. 

Conditions  that  would  permit  flies  to  come  in  contact  with 
milk  or  the  cans  are  common  in  dairies. 

Common  practice  in  connection  with  the  care  of  utensils 
leaves  many  opportunities  for  contamination  by  polluted  water. 
Oftentimes,  the  milking  utensils  are  not  scalded  after  the  even- 
ing's milking,  but  are  merely  rinsed  in  cold  water.  The 
scalding  given  utensils  is  very  apt  to  be  inefficient  and  does 


46  EPIDEMIC  DISEASES  TRANSMITTED  BY  MILK. 

not  protect  against  the  dangers  of  water.  Poor  scalding  is  a 
serious  matter  in  connection  with  bottles  that  may  have  been 
in  the  sick  room.  Water  may  get  directly  into  the  milk  from 
leaks  in  milk  coolers,  or  by  intentional  adulteration.  The 
distributing  stations  in  the  city  and  various  places  wrhere  milk 
is  sold,  furnish  their  quota  of  opportunities  for  the  infection 
of  milk. 

Detection  of  milk-borne  typhoid  fever  epidemics.  Milk-borne 
epidemics  are  most  quickly  detected  through  a  system  of  ascer- 
taining early  the  facts  regarding  the  possible  sources  of  infec- 
tion among  the  reported  cases.  The  health  officer  should  keep 
a  card  for  each  dairyman,  and  post  up  the  cases  occurring 
among  his  present  patrons,  or  those  that  took  the  milk  at  any 
time  within  a  month  previous  to  attack.  An  unusual  number 
will  direct  attention  to  the  necessity  for  an  investigation  (39). 
A  large  proportion  of  children  among  those  infected  would 
place  the  milk  supply  under  particular  suspicion. 

Bacteriological  examinations  are  not  available  for  antici- 
pating milk-borne  trouble,  nor  usually  for  demonstrating  the 
presence  of  the  organisms  in  the  milk.  The  technical  diffi- 
culties are  too  great  to  take  up  the  search  for  the  typhoid 
organism  in  the  hope  of  obtaining  decisive  useful  results.  The 
same  holds  true  of  the  examination  of  water,  in  connection 
with  a  typhoid  epidemic.  In  the  case  of  both  milk  and  water, 
one  difficulty  lies  in  the  fact  that  the  organisms  may  not  be 
present  at  the  time  suspicion  is  aroused.  The  facts  must  be 
determined  by  epidemiological  evidence.  The  writer  has  found 
very  useful  a  3  by  5-inch  card  printed  for  the  reception  of 
information  on  the  following  points,  slightly  changed  from  one 
used  in  working  up  the  Palo  Alto  epidemic  (8). 

STATE   HYGIENIC   LABORATORY. 
UNIVERSITY   OF   CALIFORNIA,   BERKELEY. 

Patient's  name Address 

(  of  first  symptoms 19 

Date  \  of  taking  to  bed  ...  19 

^of  physician's  first  visit  19 

Age sex color nationality 


•  W  r*  I  V  C.  K  a  i    |    T    • 

V  s 

^^iJFORNli^/ 


SOURCES  OF  THK  CONTAMINATION  OF  MILK. 


47 


Place  of  work,  business,  or  school  ........................ 

Physician  while  ill  .................................... 

Health  before  attack  ...................................... 

Out  of  town  (date).... 

Patient  discharged  by  physician  (date)  ...................... 

f  Chills  Pain  in  Bowels          Tongue 

]  Vomiting  Nosebleed  Delirium 

1  Headache  Diarrhoea  or  Eruption 

(  Fever  Constipation  Spleen 


0 


Constipation 

[REVERSE.] 
TYPHOID  FEVER. 

Examination  No  ..........  .  ......... 

Widal  reaction  : 

Made?  ........  Date  when  \  Date  when 

{Yes  or  No)    Positive)  ............  Suggestive 

Complications  .............. 

Drinking  Water         -™  Milkman 


Date  when 
Negative 


Previous  cases  in  the  house 
Has  patient  visited  other  cases? 
Privy  or  water  closets..... 
What  probable  sources  of  infection 
What  possible  sources  of  infection 
Remarks  ... 


Plumbing 


A  more  elaborate  blank  for  data  is  employed  by  the  Hygienic 
Laboratory,  U.  S.  Public  Health  and  Marine  Hospital  Service, 
in  the  study  of  typhoid  fever  in  the  District  of  Columbia  (29): 


PUBLIC    HEALTH    AND   MARINE    HOSPITAL   SERVICE  —  HYGIENIC 

LABORATORY. 


TYPHOID  FEVER  CASE  CARD. 

Date  of  investigation Case  No. 

Name 

Age....: Color Sex Nationality 

Probable  date  of  onset Date  of  definite  symptoms 

Name  and  address  of  physician  :    

Residence 

Residence  in  D.  C 

Residence  when  taken  sick....  ....from ....to 


48 


EPIDEMIC  DISEASES  TRANSMITTED  BY   MILK. 


Previous  residences... from to 

Subsequent  residences from to. 

Temporary  absences  from  D.  C.  within  30  days  prior 

Number  of  occupants Ages 

who  have  had  typhoid When? 

Newcomers  in  house  within  three  months  prior 

had  typhoid  ?..„.... 
Servants — 

White:     Resident Typhoid?. 

Non-resident.. Typhoid? 

Colored:    Resident Typhoid?. 

Non-resident Typhoid?. 

Typhoid  at  homes  of  servants When? 

Disposal  of  sewage  ... W.  C.  in  house..... 

W.  C.  in  yard Privy .  .     Location 

General  sanitarv  condition  of  residence 


OCCUPATION. 


Place 

Other  cases 


...  from 


to 


WATER  WITHIN  30  DAYS  PRIOR. 

Solely Principally  

Occasionally 

FOOD  WITHIN  30  DAYS  PRIOR. 

Where  taken 

Milk  (how  used) From ; 

Boiled?  Pasteurized? 

Ice  Cream? Where?. 

Uncooked  fruits  and  vegetables 

Shellfish 

CONTACTS. 

Association  30  days  prior  with  patients  in  febrile  stage 

with  suspected  cases 

with  persons  who  have  had  typhoid  within  6  months 

1  year  

2  years  

3  years : 

4  years  

5  years  ... 

Association  30  days  prior  with  persons  in  contact  with  patients  in  febrile 

stage. 
Treatment  of  stools  and  urine  of  patients 


SOURCES  OF  THE  CONTAMINATION  OF  MILK.  49 

Other  precautions 
Remarks .... 

Summary 

Signature 

In  tracing  back  the  milk  from  the  patient  to  the  source,  it 
will  be  found  that  many  milk  routes  may  derive  their  supply 
in  part  or  whole  from  the  dairy  under  suspicion.  Record  of 
the  facts  is  facilitated  by  making  a  diagram  with  lines  indicat- 
ing the  course  of  the  various  milk  supplies  from  the  producer 
to  the  distributing  station  and  on  to  the  milk  routes.  At  the 
dairy  under  suspicion,  the  inquiries  and  observations  that 
might  be  made,  and  corrective  measures  to  be  required,  are 
obvious.  A  dairy  can  by  no  means  be  freed  from  suspicion 
even  if  no  typhoid  patients  or  convalescents  are  found  there. 
Widal  tests  might  bring  to  light  a  convalescent  from  a  mild 
unrecognized  attack.  There  is  always  the  possibility  that  the 
infection  of  the  milk  has  resulted  from  a  bacilli  carrier  and  to 
detect  such  a  person  requires  a  bacteriological  examination  of 
the  feces  and  urine.  A  case  of  infection  of  milk  from  a 
typhoid  bacilli  carrier  has  recently  occurred  in  Washington, 
B.C. 

Berkeley,  Cal.,  outbreak.  A  small  milk-borne  epidemic  that 
has  been  brought  to  the  attention  of  the  writer  illustrates  well 
the  bad  conditions  that  may  prevail  (35). 

During  the  last  half  of  October,  1906,  there  were  20  cases 
of  typhoid  fever  reported  to  the  health  officer.  A  study  of 
the  cases  with  reference  to  water  supply  had  eliminated  that 
source  of  infection  from  consideration,  and  information  was 
secured  that  many  of  these  cases  had  very  likely  been  con- 
tracted in  a  nearby  city  where  typhoid  was  prevalent.  Ten 
of  the  cases,  reported  from  October  15th  to  29th,  were  all  sup- 
plied with  milk  from  the  same  dealer.  The  last  case  of  typhoid 
on  this  milk  route  was  a  son  of  the  dairyman,  who,  but  a  few 
days  before,  had  been  delivering  milk. 

A  visit  to  the  home  where  he  lay  sick  revealed  dangerous 
conditions.  No  professional  nurse  was  employed.  The  privy, 


50 


EPIDEMIC  DISEAvSES  TRANSMITTED  BY  MILK. 


a  temporary  affair,  had  no  vault  and  no  protection  from  flies. 
Not  ten  feet  from  it,  the  milk  cans  were  washed  in  a  tem- 
porary shed.  In  this  was  found  a  washtub  filled  with  milky 
water,  indicating  that  it  had  recently  been  used  for  milk  cans. 
These  conditions  are  shown  in  Fig.  8. 


Fig.  8.     Laundry  in  which  milk  cans  were  washed. 

The  family  washing  on  the  clothes  line,  and  washboard  in 
the  shed  by  the  tub,  indicated  that  the  tub  was  also  utilized 
for  laundry  purposes.  Some  eighteen  delivery  cans,  measures, 
etc.,  were  on  pegs  nearby.  Water  for  scalding  cans  was  heated 
over  a  fire  in  a  small  tank,  supported  by  a  few  bricks.  The 
supply  of  water  from  this  source  would  be  ridiculously  inade- 
quate for  the  proper  scalding  of  utensils.  The  general  condi- 
tions are  shown  in  Fig.  9.  The  building  on  which  the  milk 
cans  hang  contained  a  case  of  typhoid  fever  on  the  second  floor, 
besides  housing  the  family,  while  the  basement  was  used  as  a 
stable.  Note  in  order,  from  left  to  right,  family  washing,  tank 
for  heating  water,  shed  (beyond  horse)  for  can  washing,  and 
privy  in  fence  corner. 


DIPHTHERIA.  51 

The  milk  delivered  by  this  dealer,  not  great  in  amount,  was 
not  brought  to  the  house  before  delivery.  The  cans  only  were 
brought  there  for  washing.  It  was  learned  that  a  carpenter 
employed  on  the  premises  had  recently  recovered  from  an  at- 
tack of  typhoid  fever.  It  is  quite  possible,  too,  that  the  boy 
who  had  been  delivering  milk  may  have  been  disseminating 
infection  previous  to  taking  to  bed.  The  dairyman  was  re- 
quired to  have  the  can-washing  done  elsewhere,  after  which 
no  further  trouble  was  traceable  to  the  dairy. 


Fig,  9.     Conditions  surrounding  a  case  of  typhoid  fever, 

The  milk  sold  by  this  dealer  was  only  a  fraction  of  the  out- 
put of  a  large  dairy,  the  product  of  which  was  mostly  sold  in 
another  city,  and  it  was  not  practicable  to  trace  it. there.  A 
visit  to  the  dairy  and  inquiry  among  physicians  near  there 
revealed  no  trouble. 

Diphtheria.  Recorded  milk-borne  epidemics  of  this  disease 
are  less  common  than  in  the  case  of  typhoid  fever.  Trask 
(32)  has  collected  important  data  concerning  51  milk-borne 
epidemics. 

The  fact  that  the  conimon  seat  of  the  disease  is  readily 
accessible  for  bacteriological  examination,  has  resulted  in  the 
accumulation  of  exact  information  regarding  the  dangers  of 
infection. 

The  clinical  case  of  diphtheria,  with  a  well-defined  membrane, 
disseminates  infection  through  any  means  that  permit  the  trans- 
fer of  saliva.  Danger  of  mfection  is  not  confined  however  to 


52  EPIDEMIC  DISEASES  TRANSMITTED  BY  MILK. 

the  recognized  clinical  case.  During  convalescence,  the  viru- 
lent bacilli  may  persist  in  the  nose  or  throat  for  months  after 
the  patient  has  been  discharged  as  cured,  unless  the  culture 
method  has  been  used  to  determine  the  time  for  release  from 
quarantine.  The  condition  is  quite  parallel  to  the  typhoid 
bacilli  carriers.  Likewise,  diphtheria  bacilli  may  be  isolated 
from  the  nose  or  throat  in  advance  of  the  appearance  of  clin- 
ical symptoms. 

The  worst  of  the  matter  is  the  fact  that  diphtheria  exhibits 
all  degrees  of  severity  down  to  examples  of  healthy  persons 
harboring  virulent  diphtheria  bacilli.  These  may  be  quite  as 
dangerous  as  the  recognized  clinical  cases.  The  appearance 
of  clinical  diphtheria  in  an  individual  is  governed  in  part  by 
the  state  of  the  resistance  of  the  individual  exposed  to  infection. 

The  significance  of  these  so-called  germ  cases  is  attracting 
careful  attention  in  the  study  of  the  spread  of  diphtheria. 
They  amount  to  not  over  4%  of  the  community  in  the  absence 
of  an  epidemic,  but  in  infected  households  the  percentage  of 
germ  cases  rises  to  507^  of  the  individuals  exposed.  Some 
cases  are  practically  always  found  in  families  where  infection 
exists.  This  class  of  unrecognized  carriers  of  infection,  rather 
than  the  recognized  cases  under  treatment,  is  regarded  as  the 
chief  source  for  the  dissemination  of  diphtheria  in  a  commu- 
nity (16,  36,  37). 

In  a  dairy,  a  convalescent  or  germ  case  may  be  a  milker. 
A  cough  or  a  sneeze,  or  any  means  by  which  saliva  may  get 
on  the  hands,  and  hence  to  the  milk,  results  in  its  contamin- 
ation with  diphtheria.  Moore  (19)  has  reported  an  epidemic 
in  Ithaca,  N.  Y.,  traceable  to  a  convalescent. 

Observations  tending  to  implicate  the  cow  as  a  source  of 
diphtheria,  are  not  supported  by  convincing  facts  (3). 

Recognition  of  milk-borne  diphtheria  epidemics.  Reported 
cases  must  be  promptly  investigated  with  reference  to  the  milk 
supply,  and  investigation  of  the  dairy  should  be  made  in  case 
of  suspicion.  Bacteriological  examinations  of  milk  rarely 
result  in  the  discovery  of  Bacillus  diphtheriae  (2,  7,  20).  At 
the  dairy,  inquiry  and  physical  examination  of  throats  should 
not  be  relied  upon  to  the  exclusion  of  taking  cultures  from  both 


DIPHTHERIA.  53 

throat  and  nose  of  all  persons  about  the  establishment.  The 
results  will  very  likely  bring"  to  light  facts  which  may  not  have 
been  recognized,  or  which  had  been  suppressed. 

The  precautions  to  be  observed  upon  the  detection  of  diph- 
theria in  a  dairy  are  obvious.  Sale  of  the  milk,  raw,  should 
be  interdicted  as  long  as  a  single  person  about  the  place  har- 
bors diphtheria  bacilli.  Certainty  on  this  point  should  be 
established  by  two  or  three  negative  cultures  at  intervals  of  a 
few  days,  each  set  being  taken  simultaneously  from  the  nose 
and  throat  of  all  individuals  concerned.  The  quickest  way  to 
resume  the  sale  of  milk  would  be  to  exclude  patients  and  germ 
cases  from  the  premises. 

Milk-borne  diphtheria  in  Oroville,  Cal.  The  writer  has  used 
cultures  to  confirm  suspicion  of  a  dairy  as  the  cause  of  an  epi- 
demic, when  no  history  of  clinical  diphtheria  could  be  elicited 
(34,  35). 

Diphtheria  was  apparently  introduced  into  the  town  by  a 
visitor  who  had  recently  recovered  from  the  disease  elsewhere. 
One  case  was  reported  on  November  14th,  shortly  after  the 
arrival  of  the  visitor  in  the  family.  No  more  cases  were  re- 
ported for  six  \veeks. 

From  December  25,  1907,  until  January  25,  1908,  cases  were 
reported  in  15  families.  Six  of  these  families  consumed  milk 

from  the  R dairy.  One  of  these  6  families  was  reported 

on  December  25th,  and  the  other  5  were  reported  during  the 
5  days,  January  15th  to  20th.  Two  other  families  gave  a  history 
of  probable  spread  from  the  families  on  the  milk  route  in  ques- 
tion. Seven  infected  families  in  town  gave  no  history  of  con- 
nection with  the  milk  route. 

The  suspicions  of  the  health  officer  were  directed  to  the  dairy 
by  the  number  of  infected  families  who  were  among  its  patrons 
and  by  the  fact  that  few  families  consuming  the  milk  escaped. 
A  considerable  portion  of  the  milk  was  used  by  two  cheap  res- 
taurants, and  if  any  cases  were  contracted  from  the  milk  in 
these  establishments,  it  was  not  possible  to  trace  them. 

The  only  people  handling  the  milk  were  a  man,  his  wife 
and  daughter.  Cultures  were  made  from  the  nose  and  throat 
of  each  one.  The  mother  and  daughter  gave  positive  cultures 


54  KPIDKMIC   DISEASES    TRANSMITTED  BY  MILK. 

from  the  throat,  while  the  man  gave  negative  results.  Bacilli 
persisted  in  the  throat  of  the  woman  for  three  weeks  in  spite 
of  constant  effort  to  clear  up  the  infection.  No  history  of 
previous  clinical  diphtheria  could  be  established,  nor  were  clin- 
ical manifestations  recognizable.  The  fact  that  the  woman 
frequently  milked  the  cows,  handled  the  milk  and  delivered  it, 
is  of  interest.  Upon  the  discovery  of  the  bacilli  carriers  at 
the  dairy,  the  local  authorities  took  measures  to  prevent  further 
contamination  of  the  milk. 

Scarlet  fever.  Knowledge  of  the  details  concerning  the  in- 
fection of  milk  with  scarlet  fever  is  restricted  some\vhat  by 
the  fact  that  there  is  no  general  agreement  as  to  the  causative 
agent  of  the  disease.  It  is  believed  that  the  infectious  material 
resides  in  the  throat,  nasal  secretions  and  skin  (21).  There 
is,  though,  good  epidemiological  evidence  that  milk  infection 
with  scarlet  fever  occurs  frequently  (32). 

Milk-borne  scarlet  fever  assumes  a  mild  type  (21).  News- 
holme  (23)  calls  attention  to  the  fact  that  "  scarlet  fever  may 
be  caused  by  infected  milk  containing  the  contagium  in  such 
an  attenuated  form  or  minute  quantity  that  no  symptoms 
manifest  themselves  except  as  anomalous  sore  throat  with 
fever." 

Investigation  of  the  source  of  .milk  supply  responsible  for 
trouble,  will  reveal  some  rather  close  connection  between  a 
case  of  the  disease  and  the  milk.  It  may  be  a  case  in  the 
house;  bottles  returned  from  a  sick-room  ;  a  convalescent,  or 
a  nurse,  or  a  patient's  milking  or  handling  milk. 

The  importance  of  milk  as  a  carrier  of  scarlet  fever  is  estab- 
lished by  convincing  evidence.  Harrington  (13)  has  reported 
a  very  extensive  milk-borne  scarlet  fever  epidemic  that  occurred 
in  Cambridge,  Boston,  and  Summerville,  Massachusetts.  In 
five  days,  485  cases  were  reported  among  the  customers  of  one 
large  dairy  company.  During  a  period  of  three  weeks  from 
the  beginning  of  the  trouble,  717  cases  were  reported  in  the 
district,  of  which  84 %  were  among  the  patrons  of  the  dairy. 
The  source  of  infection  was  traced  to  a  man  employed  by  the 
dairyman  to  taste  milk,  and  who  used  the  same  spoon  in  sam- 
pling each  lot  of  milk.  The  daughter  of  this  man  was  in  the 


G ASTRO- INTESTINAL  INFECTIONS.  55 

desquamating  stage  of  scarlet  fever,  and  he  himself  showed 
markedly  prominent  papilla?  of  the  tongue.  Trask  (32)  has 
collected  information  concerning  125  milk-borne  scarlet  fever 
epidemics. 

Castro-intestinal  infections.  The  subject  of  clean  milk  in 
its  relation  to  health  has  been  widely  discussed  in  connection 
with  the  subject  of  infant  feeding.  One-third  to  one-half  of 
all  deaths  under  "one  year  are  due  to  gastro-intestinal  disorders. 
The  very  heavy  infant  mortality  from  this  class  of  diseases 
has  occasioned  careful  scrutiny  into  the  causes  contributing 
thereto.  It  has  been  shown  that  75%  to  85%  of  those  dying 
from  this  cause  are  artificially  fed.  During  the  summer  the 
deaths  from  this  cause  rise,  while  those  from  other  causes 
remain  stationary.  In  Paris,  "the  diarrheal  death  rate  in 
breast-fed  infants,  varies  from  a  minimum  of  2  per  thousand 
in  winter  to  a  maximum  of  but  20  per  thousand  during  the  hot 
months  ;  the  diarrheal  deaths  of  the  artificially  fed,  fluctuate 
from  a  minimum  of  12  per  thousand  in  winter  to  a  maximum 
of  158  per  thousand  in  the  summer  "(31).  The  striking  differ- 
ence here,  leads  to  the  suspicion  that  the  food  is  to  blame. 

Evidence  of  the  injury  done  by  cow's  milk  in  this  connection 
has  not  been  completely  worked  out  with  reference  to  the  spe- 
cies concerned.  Suspicion  has  been  directed  against  the  pep- 
tonizing  organisms,  B.  coli,  B.  proteus,  streptococci,  etc.,  or  to 
toxic  products  resulting  from  their  growth. 

Streptococci  as  a  cause  of  gastro-intestinal  disturbances  have 
been  incriminated  by  agglutination  experiments  with  the  organ- 
isms found  in  the  feces.  It  has  been  found  that  the  serum  of 
patients  develops  a  specific  agglutinating  power  for  certain 
strains'  of  streptococci  found  in  the  feces  (6).  Streptococci 
are  demonstrable  in  practically  all  raw  market  milk.  The 
difficulties  of  recognizing  pathogenic  streptococci  in  milk  are 
very  great,  because  of  the  close  resemblance  of  the  common 
lactic  acid  producing  bacteria.  Streptococcus  infections  of  the 
cow's  uclder  are  very  common  and  there  is  ample  opportunity 
for  the  infection  of  market  milk  (27).  The  subject  is  more 
completely  discussed  in  Chap.  VII. 

Evidence  has  been  adduced  from  observation  of  the  different 


56  EPIDEMIC  DISEASES  TRANSMITTED   BY  MILK. 

effects  of  clean  and  of  highly  polluted  milk  in  infant  feeding. 
Clinical  studies  have  shown  that  in  hot  weather  children  do 
the  best  on  good  milk,  and  the  worst  on  bad  milk  (26).  The 
marked  decline  in  infant  mortality  in  Xew  York  City,  due  for 
the  most  part  to  the  decline  in  mortality  from  summer  diarrhea, 
bears  a  close  relation  to  the  adoption  of  methods  for  rendering- 
milk  safe  (9).  Goler  (ll)  has  shown  the  very  striking  effect 
of  reducing  the  bacterial  content  of  a  city  milk  supply,  and 
has  shown  a  remarkable  coincidence  of  simultaneous  decline 
of  both  bacterial  count  and  infant  death  rate.  The  importance 
of  house  infection  in  epidemic  diarrhea,  has  been  emphasized 
by  Newsholme  (24) .  He  believes  that  the  bulk  of  the  infection 
in  epidemic  diarrhea  is  derived  in  some  way  within  the  house, 
and  not  derived  from  the  farm.  Sandilands  holds  similar 
views  (30).  In  proportion  to  the  number  of  consumers,  he 
noted  more  diarrhea  in  infants  fed  on  Nestle' s  food  containing 
a  few  bacteria,  than  those  on  cow's  milk  with  phenomenal 
numbers  of  bacteria.  He  believes  the  disease  to  result  from 
food  infection,  generally  from  the  excrement  of  a  patient.  He 
emphasizes  the  importance  of  flies  as  agents  in  the  transmission 
of  infection. 


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58  EPIDEMIC  DISEASES  TRANSMITTED   BY  MILK. 

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tions of  New  York  City  :  a  clinical  and  bacteriological  stud}-.      Archiv. 
Fed.,  December,  1903. 

27.  REED  and  WARD.       The  significance  of  the   presence  of   strepto- 
cocci in  market  milk.     Amer.  Med.,  Vol.  V,   1903,  No.  7,  p.  256. 

28.  ROSENAU,  IvUMSDENand  KASTI.E.     Report  on  the  origin  and  pre- 
valence of  typhoid  fever  in  the  District  of  Columbia.     Bui.  No.  35,  Hyg. 
Lab.,  r.  S.  Pub.  Health  and  Mar.  Hosp.  Sen'.,  Washington,  D.  C.,  1907. 

29.  ROSENAU,  I^UMSDEN  and  KASTLE.    Report  No.  2  on  the  origin  and 
prevalence  of  typhoid  fever  in  the   District  of  Columbia.       Bui.  No.  44, 
Hyg.  Lab.,  U.  S.  Pub.  Health  and  Mar.  Hosp.  Serv.,  Washington,  D.  C., 
1908. 

30.  SANDII^ANDS.     Epidemic  diarrhoea  and  the  bacterial    content  of 
food.    Jour.  Hyg.  (Cambridge),  Vol.  VI,  1906,  p.  77. 

31.  SCHERESCHEWSKY.     Infant  feeding.      Bui.  No.  41,  Hyg.  Lab., 
U.  S.  Pub.  Health  and  Mar.  Hosp.  Serv. ,  Washington,  D.  C.,  1908,  p.  631. 

32.  TRASK.     Milk   as  a  cause  of  epidemics  of  typhoid   fever,    scarlet 
fever  and  diphtheria.       Bui.  No.  41,  Hyg.  Lab.,  'U.  S.  Pub.  Health  and 
Mar.  Hosp.  Serv.,  Washington,  I).  C.,  1908,  p.  21. 

33.  TRASK.     Milk  in  its  relation  to  infectious  diseases.     Jour.  Amer. 
Med.  Assoc.,  Vol.  IvI,  1908,  No.  18,  p.  1491. 

34.  WARD.     Notes  on  diphtheria.     Monthly  Bui.  Cal.  State  Board  of 
Health,  Vol.  Ill,  1908,  No.  10,  p.  110. 

35.  WARD.     Report  of  the  department  of  hygiene.      Twentieth  Bien- 
nial Report  of  the  State  Board  of  Health  of  California. 

36.  WARD  and  HENDERSON.     The  control   of  diphtheria  in  a  public 
school.     Cal.  State  Jour.  Med.,  August,  1907. 

37.  WESBROOK.      Diphtheria  infection  in  Minnesota.     Jour.  Amer. 
Med.  Assoc.,  March  25,  1905. 

38.  W HIPPIE.     Typhoid   fever,  its  causation,  transmission   and   pre- 
vention.    New  York  :  John  Wiley  &  Sons,  1908. 

39.  WOODWARD.     The   municipal   regulation  of  milk   supply  of  the 
District  of  Columbia.     Bui.  No.  41,  Hyg'.  Lab.,  f\  S.  Pub.   Health  and 
Mar.  Hosp.  Serv.,  Washington,  D.  C.,  1908,  p.  679.  - 


CHAPTER  IV. 


BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE 
DISEASES. 


Bovine  tuberculosis.   (The  subject  of  bovine  tuberculosis  and 
its  relations  to  the  milk  supply  cannot  be  adequately  discussed    /2 
without  a  consideration  of  the  relations  of  the  disease  in  its 
purely  economic  aspects.  ) 

Losses  to  the  live  stock  industry.  (The  disease  is  a  tremendous 
source  of  loss  to  the  live  stock  industry,  and  worse  yet,  the 
majority  of  those  men  suffering  the  loss  have  not  awakened  to 
the  idea  of  the  possibility  of  prevention.  Precautions  for  the 
control  of  tuberculosis  have  not  yet  been  generally  recognized 
as  a  necessary  detail  in  the  management  of  the  live  stock  or  dairy 
business.  Losses  are  sustained  by  the  decrease  in  production 
from  diseased  animals  by  death,  long  before  the  expiration  of 
the  natural  life  period,  and  by  condemnation  of  carcasses  in 
the  abattoir,  in  cases  where  an  adequate  meat  inspection  system 
is  maintained  (17).  These  facts  have  been  recognized  by  a 
few,  and  the  means  of  transmission  have  been  determined,  even 
though  the  facts  have  not  been  acted  upon  in  the  United  States 
extensively  enough  to  check  the  disease.} 

Transmission  by  milk.  ( Milk  is  one  great  factor  in  the  spread 
of  tuberculosis  among  cattle.  Slaughter-house  statistics  gath- 
ered from  observations  on  pregnant  animals  have  demonstrated, 
if  such  demonstrations  were  needed,  that  tuberculosis  is  very 
rarely  inherited.  The  common  practice  in  raising  dairy  calves 
has  been  for  a  long  time  to  separate  them  from  the  cows  early 
and  feed  them  on  skim-milk.  It  is  under  these  conditions  that 
an  appalling  amount  of  infection  of  calves  occurs  (37).  The 
recognition  of  this  source  of  tuberculosis  and  its  elimination 
by  heating  the  milk,  has  afforded  the  basis  for  the  most  prac- 


60      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

ticable  scheme  yet  devised  for  the  control  of  tuberculosis, — 
the  Bang  method  (21,  22,  23,  34,  35,  36,  38,  39,  54). 

Infection  of  swine.  (^But  the  tubercular  cow  is  not  merely  a 
menace  to  her  young  through  the  milk,  but  also  casts  a  blight 
upon  the  industry  of  pork  production.  The  pig  is  particularly 
susceptible  to  bovine  tuberculosis.  In  districts  where  it  is  the 
common  practice  to  feed  pigs  on  skim-milk  and  whey,  the 
results  occasion  the  condemnation  of  such  a  high  per  cent,  of 
carcasses  that  buyers  have  learned  to  avoid  certain  districts  on 
this  account.  In  any  event,  they  pay  a  price  for  pork  lowered 
in  anticipation  of  their  losses  from  condemned  carcasses  or 
parts. 

Milk  is  not  the  only  common  means  for  the  transmission  of 
tuberculosis  by  cattle.,,  In  the  corn  belt,  pigs  are  raised  in 
association  with  beef  cattle,  so  that  they  may  utilize  the  feces 
of  cattle  for  feed.  The  magnitude  of  the  losses  occasioned  in 
this  way  has  drawn  attention  to  the  matter  of  contamination 
by  feces  as  a  source  of  the  tubercle  bacilli  in  milk  (41,  42,  45). 

Insidious  onset.  The  insidious  nature  of  the  disease  masks 
its  presence  and  wholly  misleads  the  dairymen  as  to  the 
number  of  his  cattle  that  are  tubercular.  A  cow  may  be  in 
fine  condition  and  apparently  perfect  health,  and  on  slaughter 
show  the  most  serious  advanced  stage  of  involvement  of  the 
internal  organs.  This  is  so  common  that  the  diagnosis  by 
physical  examination  by  a  veterinarian  is  entirely  unsatisfactory. 

Conditions  governing  prevalence .  The  prevalence  of  tubercu- 
losis in  herds  seems  to  depend  to  a  large  extent  upon  the 
number  of  opportunities  that  have  been  offered  for  the  possible 
introduction  of  infection.  Small  herds  which  have  been  built 
up  of  calves  raised  on  their  mothers'  milk,  will  be  found  in  the 
best  condition  (55).  The  large  herds  supplying  city  milk  are 
conducted  upon  a  different  plan,  Dry  cows  are  frequently 
i»*  sold,  and  their  place  taken  by  cows  which  have  been  bought 
shortly  before  calving.  Calves  are  butchered,  for  whole  milk 
is  too  precious  to  feed  them  and  no  skim-milk  is  available. 
Under  these  conditions,  there  is  every  opportunity  offered  for 
the  introduction  of  tuberculosis.  Among  the  dairies  in  which 
calves  are  raised  on  skim-milk,  a  different  source  of  infection 


BOVINE  TUBERCULOSIS.  61 

is  afforded.  It  is  the  practice  for  dairymen  supplying  cream- 
eries to  take  back  skim-milk  to  feed  to  the  calves.  This  skim- 
milk  is  mixed  indiscriminately  at  the  creamery,  and  thus  a 
ready  means  for  the  dissemination  of  the  disease  from  herd  to 
herd  is  afforded.  The  heating  of  skim-milk,  whey,  etc.,  at 
the  factories,  to  kill  the  tubercle  bacilli  before  distribution  to 
the  dairymen  for  feeding  purposes,  is  an  important  measure 
for  restricting  the  spread  of  the  disease.  It  has  been  made 
compulsory  in  some  states. 

Prevalence  in  herds.  /It  is  rarely  that  figures  on  the  number 
of  reacting  animals  in  large  herds  supplying  market  milk  are 
available  ;  for  the  conditions  are  so  bad  that  owners  are  cautious. 
From  reliable  sources,  the  writer  has  learned  of  herds  of  one  to 
two  hundred  cows  showing  90%  reacting.  Averages  including 
results  from  small  herds  are  lower  .J)  /In  New  York  State  figures  . ., 
compiled  from  results  of  testing  unuer  the  supervision  of  the 
Commissioner  of  Agriculture,  and  from  tests  by  private  prac- 
titioners, show  32%  of  the  cows  reacting.  The  disease  was 
found  in  61%  of  the  herds  tested  (22).) ^Recent  tests  of  cows 
supplying  Washington,  D.  C.,  show  18.6%  reacting.^)  These 
figures  are  lower  than  true  conditions,  for  the  cows  tested 
were  either  in  herds  where  efforts  to  eradicate  the  disease 
were  in  progress,  or  where  the  owner  had  no  suspicion  of  ser- 
ious trouble.  The  writer  encountered  practically  the  same 
figures  in  Berkeley,  Cal.,  among  herds  where  the  owners  did 
not  refuse  permission  to  test.  Among  1022  cows  in  22  herds 
in  California,  Dr.  Haring  and  the  writer  have  found  31.9% 
reacting.  (  Eighty- two  per  cent,  of  the  herds  were  found  to 
contain  infected  animals.  )  The  figures  are  compiled  only  from 
results  of  whole  herds,  tested  for  the  first  time.  Of  71  cows 
pastured  on  vacant  lots  in  Berkeley,  only  8%  reacted  (55). 
These  figures  concerning  the  prevalence  of  tuberculosis  among 
cattle  in  California  were  derived  from  results  obtained  largely 
in  herds  in  the  San  Francisco  Bay  region  furnishing  city  milk 
supply.  It  is  not  permissible  to  generalize  from  them  regard- 
ing the  prevalence  of  the  disease  among  cattle  elsewhere,  in 
herds  managed  differently. 


62       BOYIXE  TrBERCTEOSIS  AND  OTHER  CATTLE  DISEASES. 

Contamination  of  milk  by  tubercle  bacilli.  The  channels  by 
which  tubercle  bacilli  are  eliminated  from  the  body  of  the 
tubercular  cow,  have  been  carefully  studied.  The  elimination 
of  tubercle  bacilli  from  the  mouth,  in  the  saliva,  is  not  of  direct 
importance  in  the  contamination  of  milk.  When  the  uterus 
is  involved,  or  the  urine  contains  tubercle  bacilli,  the  proba- 
bility of  the  infection  of  the  milk  is  great.  The  tubercular 
udder,  whether  diseased  so  badly  as  to  permit  detection  or 
so  slightly  as  to  escape  detection  by  physical  examination,  gives 
off  tubercle  bacilli.  In  this  connection,  the  conclusions  of 
Mohler  (19)  bearing  on  the  point  at  issue,  are  quoted  : 

"From  the  results  of  the  experiments  conducted  in  this  Ia1x>ratory  as 
well  as  from  the  majority  of  similar  investigations  quoted  in  this  article, 
the  following  conclusions  regarding  the  infectiousness  of  milk  from  tuber- 
culous cows  seem  justifiable  : 

"1.  The  tubercle  bacillus  may  be  demonstrated  in  milk  from  tuber- 
culous cows  when  the  udders  show  no  perceptible  evidence  of  the  disease. 
either  macroscopically  or  microscopically. 

"  2.  The  bacillus  of  tuberculosis  maybe  excreted  from  such  an  udder 
in  sufficient  numbers  to  produce  infection  in  experimental  animals  both 
by  ingestion  and  inoculation. 

"3.  That  in  cows  suffering  from  tuberculosis  the  udder  may,  there- 
fore, become  infected  at  any  moment.- 

' '  4.  The  presence  of  the  tubercle  bacillus  in  the  milk  of  tuberculous 
COWTS  is  not  constant,  but  varies  from  day  to  day. 

"  5.  Cows  secreting  virulent  milk  may  be  affected  with  tuberculosis  to 
a  degree  that  can  be  detected  only  by  the  tuberculin  test. 

"6.  The  physical  examination  or  general  appearance  of  the  cow  can- 
not foretell  the  infectiveness  of  the  milk. 

"7.  The  milk  of  all  cows  which  have  reacted  to  the  tuberculin  test 
should  be  considered  as  suspicious,  and  should  be  subjected  to  steriliz- 
ation before  using. 

"8.  Still  better,  tuberculous  cows  should  not  be  used  for  general  dairv 
purposes. ' ' 

I  Ostertag  (28)  has  reached  contradictory  conclusions,  but  in 
view  of  all  the  facts  available  at  present,  the  conditions  encoun- 
tered by  him  must  be  regarded  as  unusual.  I  /It  has  been  shown 
that  an  udder  so  slightly  diseased  as  to  Be  detected  only  on 
microscopic  examination  of  the  tissues,  yielded  tubercle  bacilli 
(29).  The  difficulty  in  determining  exactly  when  an  udder  is 


BOVINE  TUBERCULOSIS.  63 

tubercular  complicates  the  matter  of  determining  whether  or 
not  tubercle  bacilli  are  found  in  milk  from  a  healthy  udder. 
In  the  light  of  facts  recently  brought  to  attention,  the  discus- 
sion of  this  matter  of  the  udder  in  its  relations  to  milk  inspec- 
tion is  not  very  profitable../ 

{  I  The  manure  of  cattle  contaminated  with  tubercle  bacilli  is 
regarded  as  an  important  source  of  tubercle  bacilli  in  milk. 
Reacting  tuberculous  dairy  cows  that  retain  the  appearance  of 
health,  may  actively  expel  tubercle  bacilli  in  the  feces  (41,  42, 
43,  46).  A  very  small  percentage  of  such  cases  in  a  herd  could 
bring  about  a  very  extensive  infection  of  the  milk.  Among 
the  possible  sources  of  the  bacilli,  understood  at  present,  are 
sputum  swallowed,  and  open  tubercular  lesions  of  the  intes- 
tines. Feces  constitute  the  most  common  contamination  of 
milk  as  demonstrated  by  observation  of  dairy  practice,  and  by 
the  microscopic  examination  of  milk  sediments.  The  presence 
of  tubercle  bacilli  in  human  feces  in  early  cases  has  been  noted 

s^   and  suggested  as  a  means  for  the  early  diagnosis  of  the  disease 

Xsi). 

r~~Tuberclc  bacilli  in  market  milk.  Anderson  (1)  found  in 
/Washington,  D.  C.,  that  6.72%  of  223  samples  examined  con- 
I  tained  tubercle  bacilli.  The  results  analyzed  according  to  the 
source  of  the  samples  showed  that  about  11  $>  of  the  dairies 
whose  milk  was  examined  showed  tubercle  bacilli.  His  meth- 
ods were  such  that  he  believes  the  results  understate  the  true 
conditions. 

Schroeder  (43)  refers  to  the  examination  of  350  samples  of 
milk  in  Washington  by  different  workers  with  the  result  that 
about  5.5%  showed  tubercle  bacilli.  About  one  dealer  out  of 
every  ten  was  intermittently  selling  tuberculous  milk.  Hess 
(9)  examined  107  samples  of  milk  in  New  York  and  found 
tubercle  bacilli  in  16%  of  the  samples.  Trask  (Ref.  33,  Chap. 
Ill)  has  collected  the  results  of  the  work  on  tubercle  bacilli  in 
done  by  a  large  number  of  investigators.  ^ 

Human  and  bovine  types  of  tubercle  bacilli. .(  The  original 
ideas  of  the  complete  unity  of  tuberculosis  in  cattle  and  in 
man  were  based  upon  the  identity  of  the  lesions  in  gross  and 
microscopic  appearance.  TUp  to  1896,  the  identity  of  the 


64      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

tubercle  bacilli  in  the  two  branches  of  the  disease  was  not 
questioned.  Then  Theobald  Smith  pointed  out  certain  differ- 
ences in  morphology,  cultural  characteristics  and  virulence 
regarded  as  characteristic  of  the  organism  in  man  and  bovines 
(47,  48).  That  these  differences  are  usually  observed,  is  a 
t  that  has  received  very,  wide  confirmation. 

Views  of  Koch.  In  1901  (13)  and  1902  (14),  Koch  very 
carefully  reviewed  the  grounds  for  the  belief  that  bovine  tuber- 
culosis is  transmitted  to  man,  and  reached  the  conclusion  that 
it  is  not  worth  while  to  combat  bovine  tuberculosis  in  the 
interest  of  the  public  health.  Koch's  paper  raised  an  extraor- 
dinary storm  of  protest,  and  likewise  stimulated  the  study  of 
the  problem  along  lines  suggested  by  his  arguments^  He 
pointed  out  very  clearly  and  conclusively  the  essential  w 
ness  of  the  evidence  frequently  accepted  as  proof  of  the  trans- 
mission of  tuberculosis  to  man.  The  very  wide  prevalence  of 
human  tuberculosis  makes  it  very  difficult  to  establish  the 
absence  of  human  infection  in  cases  where  cattle  are  suspected 
as  the  source.  He  laid  down  certain  conditions  that  must  be 
satisfied  before  transmission  would  be  admitted  as  proven,  and 
these  dicta  are  so  stringent  that  it  would  be  very  difficult  to 
find  any  case  conforming  to  them. 

It  has  been  observed  by  Koch  that  milk-borne  tuberculosis 
does  not  correspond  to  the  other  milk-borne  diseases  in  the 
matter  of  the  sudden  explosive  occurrence  of  cases  among 
those  consuming  the  milk.  The  known  peculiarities  of  tuber- 
culosis, such  as  its  deliberate  onset,  and  especially  the  concep- 
tion of  latency  of  infection  -introduced  by  von  Behring  (52), 
rather  impair  the  value  of  the  point  as  an  argument  against 
the  transmission  of  tuberculosis  by  milk. 

Bovine  tubercle  bacilli  in  wan,  Koch  pointed  out  that  the 
recognition  of  bovine  and  human  types  of  tubercle  bacilli  gave 
a  sound  basis  for  determining  the  source  of  the  disease  in 
human  cases.  It  is  along  this  line  that  the  most  conclusive 
evidence  of  the  transmission  of  the  disease  has  been  obtained. 
The  literature  shows  between  forty  and  fifty  cases  in  which 
bovine  tubercle  bacilli  have  been  isolated  from  infants  and 
children.  This  was  conceded  in  1907  by  Theobald  Smith  (49), 


BOVINB  TUBERCULOSIS.  65 

whose  attitude  is  conservative  and  critical.  In  1908  he  stated  : 
"  and  it  has  been  found  that  perhaps  half  of  certain  kinds  of 
tuberculosis  in  children,  such  as  those  of  the  glands  of  the 
neck  and  abdomen,  are  due  to  infection  from  milk."  (50) 
/Insufficient  work  has  been  done  to  determine  the  percentage 
of  human  tuberculosis  caused  by  bovine  tuberculosis.  The  Brit- 
ish Royal  Commission  found  the  bovine  type  14  times  in  60 
cases  of  human  tuberculosis  investigated  by  it  (5).  The  sig- 
nificant fact  is  that  here  is  indisputable  evidence  to  satisfy  the 
most  conservative  that  tuberculosis  is  transmitted  from  cattle 
to  man.\ 

Intermediate  types  of  tubercle  bacilli.  Some  observers  believe 
that  the  study  of  a  series  of  tubercle  cultures  reveals  interme- 
diate types  varying  from  the  extremes  exhibited  by  human 
and  bovine  cultures  (3,  7,  20,  43).  These  intermediates  have 
been  observed  in  both  cattle  and  man.  The  observation  has  led 
to  the  conclusion  that  certain  characters  of  the  tubercle  organ- 
isms are  exceedingly  variable.  For  instance,  a  bovine  strain 
in  a  child  might  after  a  time  be  modified  by  environment  so 
much  as  to  disguise  its  original  source.  If  this  point  of  view 
is  taken,  bacteriological  distinctions — the  only  ones — between 
tuberculosis  in  cattle  and  man  break  down,  and  the  importance 
conceded  to  bovine  tuberculosis  in  connection  with  the  public 
ealth  is  consequently  increased. 

Channels  of  infection.  Alimentary  infection  was  formerly 
thought  to  give  rise  necessarily  to  primary  tuberculosis  in  the 
mesenteric  lymph  nodes.  The  rare  occurrence  of  this  con- 
dition was  used  by  Koch  as  an  argument  to  prove  that  tuber- 
culosis in  children  does  not  frequently  originate  from  milk. 
Experimental  work  with  reference  to  this  point  has  shown  that 
the  primary  lesion  in  animals  need  not  necessarily  occur  in  a 
mesenteric  lymph  node.  Tubercle  bacilli  from  the  intestinal 
tract  may  travel  to  the  lungs  via  lymph  node,  thoracic  duct 
and  blood,  causing  the  primary  lesion  in  the  capillaries  of  the 
lung  or  elsewhere  (30).  It  is  also  believed  that  infection 
may  enter  through  the  tonsils  and  cause  tubercular  involve- 
ment of  organs  anterior  to  the  diaphragm  without  ever  travers- 
ing the  abdominal  organs.  There  is  a  growing  belief  based  on 


66      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

the  work  in  meat  inspection,  that  alimentary  infection  plays  a 
very  important  part  in  the  infection  of  cattle  and  hogs.  Such 
observations  have  been  made  the  basis  of  an  assault  on  the 
older  theory  of  exclusive  inhalation  infection  of  the  lung,  and 
tend  to  exalt  the  importance  of  alimentary  infection. 

International  Congress  of  1908.  At  the  International  Con- 
gress on  Tuberculosis  at  Washington  in  1908,  Koch  stated 
that  he  believed  bovine  tuberculosis  to  constitute  a  minor 
source  of  tuberculosis  in  man.  He  regarded  pulmonary  tuber- 
culosis (phthisis)  as  the  cause  of  eleven-twelfths  of  the  deaths 
from  tuberculosis  and  he  was  not  convinced  that  the  bovine  type 
of  tubercle  bacillus  has  been  shown  to  produce  that  type  of 
tuberculosis  in  man.  He  disparaged  the  importance  of  the 
cases  in  which  the  bovine  type  of  bacilli  have  been  found  in 
glands  on  the  ground  that  glandular  tuberculosis,  in  compari- 
son with  pulmonary  tuberculosis,  is  a  minor  cause  of  fatality. 
On  the  point  concerning  the  frequency  of  primary  abdominal 
and  cervical  tuberculosis,  the  belief  was  held  by  many  of  the 
delegates  that  these  types  of  tuberculosis  are  much  more  fre- 
quent and  important  than  believed  by  Koch  (6). 

The  portion  of  the  resolutions  of  the  Congress  bearing  on 
bovine  tuberculosis  is  as  follows  : 

<i  3.  *  *  Again,  the  utmost  efforts  should  be  continued  in  the  struggle 
linst  tuberculosis  to  prevent  conveyance  from  man  of  tuberculous  in- 
tion  as  the  most  important  cause  of  the  disease.  Further,  preventive 
'measures  must  be  continued  against  bovine  tuberculosis,  and  the  possi- 
bility of  the  propagation  of  this  to  man  should  be  recognized."  (31) 

Tuberculosis  in  Japan.  The  tendency  to  regard  bovine  tuber- 
culosis as  the  chief  source  of  tuberculosis  in  human  beings,  is 
counteracted  by  certain  evidence  (1*2). 

In  Japan  very  little  cow's  milk  is  used  for  food,  the  average 
amount  consumed  daily  per  capita  being  only  2.825  cc.  Espe- 
cially is  it  rarely  employed  as  food  for  children.  Human 
tuberculosis  is  as  frequent  in  Japan  as  in  Europe  and  America. 
There  the  disease  in  man  dates  back  to  the  earliest  chronicles. 
Tuberculosis  occurs  only  in  foreign  cows  and  their  crosses  with 
native  cattle.  Pure  native  cattle  are  relativelv  immune  and 


MEASURES  AGAINST  BOVINE  TUBERCULOSIS.  67 

no  tuberculosis  was  known  among  Japanese  cattle  until  the 
introduction  of  foreign  stock  about  thirty-five  years  ago. 

Present  status  of  controversy.  That  tuberculosis  may  be 
transmitted  from  cattle  to  the  human  being,  is  an  accepted  fact 
not  even  denied  by  Koch.  The  differences  of  opinion  concern 
the  extent  to  which  it  occurs,  and  these  in  turn  depend  upon 
the  conception  of  the  characters  that  may  be  accepted  as  defin- 
ing an  organism  of  bovine  origin.  On  the  whole,  the  belief  is 
that  tuberculosis  in  cattle  constitutes  a  minor  source  of  tuber- 
culosis in  man. 

Protection  of  the  milk  supply.  The  situation  warrants  the 
enforcement  of  firm,  effective  measures  for  the  protection  of  the 
milk  supply.  The  proven  facts  excite  both  disgust  and  appre- 
hension on  the  part  of  the  consumer.  To  correct  such  condi- 
tions is  a  very  legitimate  function  of  food  inspection  service. 
No  question  is  raised  as  to  the  propriety  of  condemning  car- 
casses for  generalized  tuberculosis,  even  though  most  meat  is 
practically  safe  when  cooked.  The  ground  for  condemnation 
is  the  abhorrence  and  fear  of  consuming  infectious  tubercular 
material.  The  same  undesirable  qualities  are  possessed  by 
milk  of  tubercular  cows,  only  worse,  for'  it  is  not  the  practice 
to  cook  milk. 

Certain  physicians  show  a  tendency  to  avoid  agitation  con- 
cerning cattle,  the  minor  source  of  tuberculosis,  for  fear  of  dis- 
tracting popular  attention  from  the  main  source  of  infection- — 
tubercular  human  beings.  This,  perhaps,  is  justifiable  in  so 
far  as  the  attitude  relates  to  the  spending  of  money.  There  is 
no  question  but  that  money  for  fighting  tuberculosis  of  man 
could  be  more  profitably  spent  than  in  attempts  to  eradicate 
tuberculosis  of  cattle  by  slaughtering  animals  and  indemnifying 
the  owners.  This  is  an  economic  matter  primarily. 

Measures  against  bovine  tuberculosis.  A  number  of  circum- 
stances combine  to  make  it  most  difficult  to  protect  effectually 
the  milk  supply  from  the  germs  of  tuberculosis.  (  The  wide 
prevalence  of  tuberculosis  among  cattle  raises  obstacles  in  the 
way  of  expense  incurred  to  the  dairymen.  A  great  many 
attempts  have  been  made  to  control  the  disease  both  in  the 
interest  of  the  public  health  and  as  a  purely  economic  measure. 


68      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

In  most  cases  great  expense  has  been  incurred  by  the  dairymen, 
with  little  permanent  benefit.  Tuberculosis  in  general  has 
kept  pace  with  the  efforts  directed  against  it,  and  in  only  a 
few  states  can  it  be  claimed  that  substantial  progress  is  being 
made  in  its  eradication.  Dairymen  have,  for  almost  a  genera- 
tion, been  harassed  by  agitation  over  the  subject  and  their  atti- 
tude towards  public  health  measures  is  one  of  indifference  or 
open  hostility.  City  milk  supply  is  derived  from  such  scattered 
sources  that  effective  administration  is  difficult.  Then,  too,  the 
individual  co\vs  comprising  the  herds  are  constantly  changing 
as  they  dry  off  and  are  replaced  by  fresh  cows.  Coupled  with 
this  it  should  be  noted  that  the  majority  of  dairymen  persist - 
-  ently  ignore  precautions  against  introducing  the  disease.\  Under 
~  these  conditions  the  temptation  is  great  to  resort  to  bribery  in 
some  cases,  or  to  legal  measures  for  the  purpose  of  invalidating 
the  ordinance.  The 'Circumstances  are  such  as  to  encourage 
laxity  in  the  enforcement  of  tuberculin  test  ordinances.  A 
sharp  distinction  should  be  drawn  between  the  meanings  of 
the  expressions  ' '  in  force  ' '  and  ' '  enforced  ' '  as  applied  to  an 
ordinance. 

Physical  examination.  While  some  advanced  cases  of  tuber- 
culosis can  be  recognized  by  physical  examination,  such  an 
examination  will  reveal  but  a  small  percentage  of  the  cases 
capable  of  disseminating  infection. 

The  idea  of  inspecting  dairy  herds  by  physical  examination 
alone  is  based  upon  the  belief  that  a  physical  examination  is 
capable  of  indicating  the  seriously  diseased  animals.  The  evi- 
dence accumulated  from  post-mortem  examinations  of  dairy 
cattle,  and  from  the  bacteriological  examination  of  feces,  con- 
troverts the  truth  of  the  assumption.  If  a  physical  examination 
is  to  be  of  use,  it  must  be  so  searching  as  to  permit  the  detec- 
tion of  all  those  animals  having  open  lesions  in  the  respiratory 
and  alimentary  tracts.  Such  results  are  not  obtainable.  Among 
the  dangerously  tubercular  animals  may  be  found  at  post- 
mortem examination  the  best  looking  cows  in  a  herd.  The 
condition  of  flesh  of  an  animal  is  worthless  as  a  guide.  The 
good  dairy  cow  certainly  is  emaciated  at  times,  and  this  in 
conjunction  with  an  old  coat  of  hair  gives  a  miserable  appear- 


MEASURES  AGAINST  BOVINE  TUBERCULOSIS.  69 

ance.  Under  the  circumstances,  emaciation  as  a  symptom  of 
tuberculosis  cannot  be  given  very  heavy  consideration.  Aus- 
cultation and  percussion  of  the  lungs  do  not  yield  the  results 
that  might  be  expected,  and  the  same  may  be  said  of  palpa- 
tion of  the  superficial  lymph  glands.  Neither  the  lungs  nor 
accessible  lymph  glands  are  necessarily  involved  in  advanced 
cases. 

Emphasis  has  been  laid  upon  the  value  of  detecting  the 
tubercular  udder,  as  if  it  were  a  very  important  factor  in  the 
contamination  of  milk.  As  a  matter  of  fact,  the  development 
of  tuberculosis  in  the  udder  to  a  degree  that  would  attract 
attention  is  very  rare.  Smith  (49)  believes  that  roughly  speak- 
ing the  udder  becomes  tuberculous  through  metastasis  in  per- 
haps 1%  of  tubercular  cows.  Muller  (27)  states  that  1.62% 
of  all  cows  slaughtered  in  Germany  show  tuberculosis  of  the 
udder.  Mammitis,  associated  with  steptococci,  is  very  com- 
mon and  causes  indurated  areas  in  the  udder  that  raise  insur- 
mountable difficulties  in  the  differential  diagnosis  by  physical 
signs.  The  bacteriological  examination  of  samples  of  milk 
from  the  suspected  udder  is  the  only  reliable  means  for  identi- 
fying tuberculosis  of  the  udder. 

In  the  discussion  of  the  tuberculosis  problem  the  idea  is 
sometimes  implied  that  the  detection  and  removal  of  the  worst 
animals  from  a  herd  will  effect  some  measure  of  improvement  in 
diminishing  the  disease.  Such  a  procedure  does  not  appreci- 
ably diminish  the  opportunity  for  the  further  spread  of  infection 
and  certainly  does  not  benefit  the  large  number  already  slightly 
affected.  Physical  examination  and  removal  of  the  con- 
demned animals  anticipates  by  a  considerable  period  the  nat- 
ural breaking  down  from  the  disease  and  results  in  the  removal 
of  some  others  less  seriously  diseased  but  which  happen  to  be 
easily  detected.  It  results  in  no  permanent  improvement  along 
the  line  of  extinguishing  the  infection. 

The  writer's  personal  experience  in  physical  examination  of 
dairy  herds  for  tuberculosis  has  been  most  unsatisfactory. 
About  300  cows  supplying  a  town  with  milk  were  examined 
once  in  each  of  two  successive  years.  Cows  showing  definite 
unmistakable  physical  signs  of  tuberculosis,  warranting  slaugh- 


70      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

ter,  were  not  found,  but  three  excited  strong  suspicion.  The 
dairymen  either  in  accordance  with  regular  practice  or  on 
account  of  the  moral  effect  of  the  inspection,  had  removed  the 
cows  that  persistently  coughed.  In  the  third  year,  the  tuber- 
culin test  revealed  the  fact  that  30%  of  the  cows  were  tubercular. 
During  work  in  another  town  in  a  group  of  64  tubercular  cows, 
only  9  showed  physical  signs  of  tuberculosis.  The  writer  does 
not  feel  that  he  is  making  a  confession  of  discreditable  incom- 
petency,  for  his  experience  is  not  unusual.  In  one  instance,  a 
recognized  expert  on  bovine  tuberculosis  examined  378  reacting 
cows  and  was  able  to  recognize  only  21  as  tubercular  by  means 
of  physical  examination. 

The  idea  of  the  efficacy  of  physical  examination  to  prevent 
the  presence  of  tubercle  bacilli  in  milk  persistently  crops  out 
in  the  discussion  of  methods  of  milk  inspection.  As  late  as 
May,  1907,  a  commission  of  physicians  made  the  following 
recommendations  to  the  Mayor  of  New  York  (10): 

' '  The  Commission  believes  that  the  essential  requirement  is  to  secure 
from  the  farm  a  safe,  clean  milk. 

"Tuberculosis. — The  risk  of  transmitting  tuberculosis  through  milk 
from  cows  to  man  is  very  slight,  unless  the  disease  in  the  cow  is  in  an 
advanced  form  or  is  present  in  the  udder.  Even  this  slight  risk  is  con- 
siderably lessened  when  such  milk  is  mixed,  as  it  generally  is,  with  that 
of  healthy  cows  before  it  is  sold.  We  believe  that  this  danger  has  been 
greatly  overestimated  in  the  public  mind  and  that  it  can  best  be  met  by 
systematic  inspection  and  condemnation  of  cows  revealing  tuberculosis 
on  physical  examination.  Certain  legislation  regarding  tuberculosis  in 
cattle  now  being  contemplated  at  Albany  has  been  carefully  considered, 
and  the  Commission  believes  that  if  suitable  legislation  can  be  secured 
with  adequate  appropriations  for  the  enforcement  of  the  same,  our  milk 
supply  in  this  respect  coming  from  the  State  of  New  York  will  be  suit- 
ably safeguarded.  Such  legislation  should  provide  for  notification  of 
city  authorities  of  the  existence  of  disease,  which  may  be  transmitted 
through  milk,  occurring  in  the  cows  or  in  the  families  or  the  persons  of 
those  handling  milk." 

""  Municipal  activity  on  the  tuberculosis  problem  will  certainly 
accomplish  nothing  worth  \vhile  if  carried  on  along  the  lines 
recommended  above.  The  statements  are  apparently  based  on 
the  faulty  assumption  that  a  physical  examination  will  reveal 
cows  affected  wTith  tuberculosis  in  an  advanced  form,  and  that 


MEASURES  AGAINST  BOVINE  TUBERCULOSIS.  71 

such  are  the  only  ones  disseminating  large  numbers  of  tubercle 
bacilli.  The  idea  is  controverted  by  a  mass  of  evidence  too 
weighty  to  be  thus  ignored.  The  Commission  betrays  a  cer- 
tain amount  of  hesitancy  in  regard  to  measures  against  bovine 
tuberculosis,  for  elsewhere  in  the  report  the  following  recom- 
mendation is  made  : 

"Pasteurization. —  Notwithstanding  after  all  safeguards  that  may  be 
imposed  by  education  and  otherwise,  there  will  be  cases  in  which  unsafe 
milk  will  be  produced  or  offered  for  sale,  and  all  such  milk  must  be 
judged  on  its  merits.  The  Commission,  therefore,  recommends  that  the 
Board  of  Health  should,  according  to  circumstances,  require  efficient 
sterilization  or  pasteurization  of  all  milk  which  it  finds  unsafe  for  con- 
sumption as  raw  milk,  on  account  of  a  suspicion  of  the  presence  of  tuber- 
culosis or  other  disease  in  the  cows  or  unsanitary  conditions  of  the  dairy 
or  a  persistent  high  bacterial  content.  But  in  every  instance  milk  so 
heated  should  be  rapidly  cooled  to -at  least  40°P\,  and  be  put  after  steril- 
ization or  pasteurization,  into  sterilized  containers  under  aseptic  precau- 
tions. The  pasteurization  of  milk  should  be  done  only  a  few  hours 
before  delivery  to  the  consumer,  and  the  container  should  be  marked 
with  the  time  and  date  of  pasteurization  and  the  degree  and  duration  of 
temperature  employed  for  the  purpose." 

Tuberculin  test.  \  The  tuberculin  test  is  the  only  available 
means  for  the  detection  of  tuberculosis  in  cattle.  )  fTurjerculin 
is  a  sterile  liquid  product  containing  a  concentrated  extract 
,a  \  of  tubercle  bacilli.  \~Trhe  subcutaneous  injection  of  a  properly 
^  standardized  dose  of  tuberculin  will  induce  a  rise  of  tempera- 
ture in  a  tubercular  animal  in  which  the  disease  isyactive,  but 
will  have  no  effect  upon  a  non-tubercular  animal.  '  The  test  is 
indispensable  in  the  control  of  the  disease  by  revealing  the  ani- 
mals in  every  stage  of  the  disease  beyond  the  incubation  period. 
/The  test  does  not  reveal  the  extent  of  the  disease  and  hence  is 
of  no  value  in  discriminating  between  tubercular  animals  dis- 
seminating infection  and  those  not?\  The  information  obtained 
furnishes  the  means  of  separating  the  healthy  from  the  diseased. 
In  view  of  the  fact  that  tuberculosis  so  frequently  develops  in 
the  animal  rapidly,  any  tubercular  animal  in  a  herd  is  pot 
tially  if  not  actually  dangerous.  It  is  a  most  difficult  matter 
to  convince  the  average  man  upon  this  point.  The  number  o 
animals  reacting  is  oftentimes  surprisingly  large  when  the 
general  appearance  of  the  herd  is  considered.  Among  those 


72      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

reacting  there  may  be  the  finest  appearing  and  best  producing 
cows  in  the  herd.  A  post-mortem  examination,  revealing  a 
small  lesion,  does  not  convince  the  layman  that  the  slaughter 
was  justified. 

New  tests  for  tuberculosis.  Of  late,  considerable  attention  has 
been  paid  to  certain  modifications  of  the  method  of  applying  the 
tuberculin  test  (25).  Among  these  are  the  intradermo  (26) 
and  ophthalmo  (56)  tests.  Their  claim  to  attention  is  based 
cmsj m p1  i ri ty-but  they  are  as  yet  in  the  experimental  stage. 

Stable  sanitation  and  tuberculosis.  Good  sanitary  conditions, 
good  ventilation,  reasonable  exercise,  good  climate,  good  food 
\  and  general  well  being  are  in  high  repute  as  measures  for 
\  restricting  and  preventing  tuberculosis  in  man.  In  some 
V  quarters  there  is  a  tendency  to  assume  that  the  bovine,  sur- 
rounded by  conditions  that  are  by  assumption  rated  as  corres- 
pondingly good,  will  be  in  a  measure  protected  from  bovine 
tuberculosis.  A  true  parallel  does  not  exist,  for  the  conditions 
favoring  the  spread  of  bovine  tuberculosis  are  such  that  the 
best  of  stables  in  the  best  of  climates  or  even  no  stable  at  all, 
will  not  prevent  the  spread  of  the  disease  (54).  Baker  (4) 
has  produced  some  very  striking  evidence  on  the  point  drawn 
from  statistics  concerning  cattle  slaughtered  under  Federal  in- 
spection in  San  Francisco. 

Tuberculin  test  ordinances.  The  object  of  municipal  legisla- 
tion is  not  primarily  the  eradication  of  bovine  tuberculosis,  but 
rather  to  ensure  a  pure  milk  supply.  The  legislation,  there- 
fore, need  go  no  farther  than  to  ensure  the  exclusion  of  milk 
of  diseased  animals  by  requiring  that  all  cows  pass  the  tuber- 
culin test  and  a  physical  examination.  Since  the  milk  supply 
comes  largely  from  without  the  borders  of  the  city,  it  would 
be  difficult,  both  legally  and  practically,  to  go  farther  than  this. 
The  dairyman  is  thus  at  liberty  to  accept  the  conditions  im- 
posed for  a  license  by  the  city,  or  to  sell  his  milk  elsewhere. 
The  plan  involves  no  compulsory  interference  with  property 
rights  and  does  not  necessarily  contribute  to  the  reduction  of 
bovine  tuberculosis  beyond  the  dairies  immediately  affected. 

Tuberculin  test  ordinances  are  in  force  in  a  number  of  Amer- 
ican cities.  Probablv  Minnesota  heads  the  list  of  states  in  the 


TUBERCULIN  TEST  ORDINANCES.  73 

number  of  cities  having  the  test.  The  list  as  given  in  the 
Minnesota  exhibit  at  the  International  Congress  on  Tubercu- 
losis, Washington,  1908,  is  as  follows:  Minneapolis,  St.  Paul, 
St.  Cloud,  Alexandria,  Duluth,  Mankato,  Litchfield,  Willmar, 
Albert  Lea  and  Winona.  Montclair,  N.  J.,  is  at  present  the 
scene  of  a  legal  struggle  between  the  dairymen  and  the  Board 
of  Health,  on  the  matter  of  the  enforcement  of  a  tuberculin 
test  ordinance.  The  Board  of  Health  of  Berkeley,  Cal.,has 
attempted  to  enforce  two  different  tuberculin  test  ordinances 
but  has  been  enjoined  by  the  courts  from  doing  so  in  each  case. 

The  complete,  impartial  enforcement  of  an  ordinance  pro- 
hibiting the  sale  of  milk  from  reacting  cattle  raises  a  host  of 
difficulties  occasioned  by  the  wide  prevalence  of  tuberculosis. 
The  condemnation  of,  say,  25%  of  the  cows  supplying  a  city, 
throws  all  the  producers  into  the  market  for  cows.  Those  for 
sale  are  those  .that  have  just  reacted.  During  the  excitement  of 
the  enforcement  of  the  tuberculin  test  ordinance,  cow  owners 
will  not  sell  cows  subject  to  the  test.  Compliance  with  the 
ordinance  means  reduction  of  the  output  of  milk.  Producers 
will  refuse  to  sell  to  the  distributors  in  the  city,  and  will  market 
the  milk  elsewhere.  The  dairies  that  at  present  are  able  to 
comply  with  a  tuberculin  test  ordinance,  represent  an  insignifi- 
cant per  cent,  of  the  milk  supply  of  our  larger  cities. 

Clean  herds  the  goal.  In  isolated  instances,  the  complete 
enforcement  of  a  tuberculin  test  ordinance  is  practicable,  and 
this  should  be  the  end  towards  which  efforts  everywhere  should 
be  directed.  The  difficulties  of  the  problem  presented  by  the 
larger  cities  must  be  met  by  a  scheme  that  will  permit  gradual 
improvement.  Even  with  a  bountiful  supply  of  healthy  cows 
available,  and  with  the  cordial  co-operation  of  the  owners  of 
herds,  the  work  of  testing  the  herds  and  eradicating  tubercu- 
losis is  a  tremendous  task  and  would  take  years.  The  con- 
tinuance of  present  conditions  must  be  discouraged,  the  public 
health  must  be  protected,  and  at  the  same  time  the  measures 
enforced  must  not  disrupt  the  milk  business. 

The  \Vashington  plan.  The  most  practicable  scheme  that 
has  been  suggested  is  the  compulsory  pasteurization  of  all 
milk  produced  from  cows  that  have  not  passed  the  tuberculin 


74      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

test.  The  suggestion  has  been  made  by  a  Milk  Conference 
appointed  by  the  Commissioners  of  the  District  of  Columbia 
(40).  The  members  of  the  conference  represented  the  various 
Federal  departments  interested  in  the  subject,  together  with  the 
dairymen.  The  conference  recommends  the  classification  of 
milk  into  three  grades,  as  follows  : 
Class  1 .  Certified  m  ilk . ' ' 

This  grade  represents  the  highest  class  of  milk,  ordinarily 
certified  by  medical  societies.  The  tuberculin  test  and  a  bac- 
terial count  of  under  10,000  per  cc.,  are  among  the  require- 
ments. (See  Chap.  IX.) 

' '  Class  2.     Inspected  milk. ' ' 

This  is  a  lower  grade  of  milk,  produced  from  tested  cows, 
and  differing  from  the  former,  chiefly,  in  that  the  conditions 
under  which  the  milk  is  produced  need  not  be  equal  to  those 
of  dairies  in  Class  1.  The  bacterial  count  shall  not  be  more 
than  100,000  per  cc. 

"  Class  3.  Pasteurized  milk.  Milk  from  dairies  not  able  to  comply 
with  the  requirements  specified  for  the  prochiction  of  milk  of  classes  1 
and  2  is  to  be  pasteurized  before  being  sold,  and  must  be  sold  under  the 
designation  'pasteurized  milk1.  Milk  for  pasteurization  shall  be  kept  at 
all  times  at  a  temperature  not  exceeding  60°F.  while  in  transit  from  the 
dairy  farm  to  the  pasteurization  plant,  and  milk  after  pasteurization  shall 
be  placed  in  sterilized  retainers  and  delivered  to  the  consumer  at  a  tem- 
perature not  exceeding  50°F.  All  milk  of  an  unknowrn  origin  shall  be 
placed  in  class  3  and  subjected  to  clarification  and  pasteurization.  No 
cow  in  any  way  unfit  for  the  production  of  milk  for  use  by  man,  as  deter- 
mined upon  physical  examination  by  an  authorized  veterinarian,  and  no 
cow  suffering  from  a  communicable  disease,  except  as  specified  below, 
shall  be  permitted  to  remain  on  an}-  dairy  farm  on  wThich  milk  of  class  3 
is  produced,  except  that  cows  \vhich  upon  physical  examination  do  not 
show  physical  signs  of  tuberculosis  may  be  included  in  dairy  herds  sup- 
plying milk  of  this  class,  although  they  may  have  reacted  to  the  tuber- 
culin test. 

' '  This  milk  is  to  be  clarified  and  pasteurized  at  central  pasteurization 
plants,  which  shall  be  under  the  personal  supervision  of  an  officer  or 
officers  of  the  health  department.  These  pasteurization  plants  may  be 
provided  either  by  private  enterprise  or  by  the  District  Government,  and 
shall  be  located  within  the  city  of  Washington." 

Elsewhere  in  the  report,  the  conference  makes  the  following 
recommendations  regarding  tuberculosis  : 


TUBERCULIN  TEST  ORDINANCES.  75 

' '  Identification  of  dairy  cattle.  That  all  cows  on  dairy  farms  produc- 
ing milk  for  the  District  of  Columbia  be  tagged,  tattooed,  or  otherwise 
marked  for  purposes  of  identification. 

' '  Tuberculin  testing  or  pasteurization  required.  That  all  milk  pro- 
duced for  use  in  the  District  of  Columbia  shall  either  come  from  cattle- 
free  from  tuberculosis  as  shown  by  the  tuberculin  test,  which  tuberculin 
test  shall  be  repeated  at  least  once  every  year,  or  be  subjected  to  pas- 
teurization under  the  supervision  of  the  health  department  in  case  the 
herd  is  not  tuberculin  tested. 

' '  New  dairy  cattle  to  be  tuberculin  tested.  That  hereafter  no  addition 
.shall  be  made  to  any  herd  producing  milk  for  use  in  the  District  of  Col- 
umbia, whether  such  herd  has  or  has  not  been  tuberculin  tested,  unless 
the  cattle  so  added  have  been  tested  with  tuberculin  and  found  to  be  free 
from  tuberculosis. 

"  Neiu  licentiates  to  have  herds  tuberculin  tested.  That  hereafter  no 
license  shall  be  granted  to  produce  milk  for  use  in  the  District  of  Col- 
umbia unless  the  herd  by  which  such  milk  is  to  be  produced  has  been 
found  by  the  tuberculin  test  to  be  free  from  tuberculosis." 

The  compulsory  pasteurization  of  all  the  milk  supply  of  a 
city  will  be  attended  with  difficulties,  but  these  are  slight  as 
compared  with  those  associated  with  the  enforcement  of  a 
tuberculin  test  ordinance.  Chicago  has  adopted  the  scheme 
of  enforcing  the  tuberculin  test,  with  the  alternative  of  pas- 
teurizing the  milk. 

Test  by  city  official.  The  testing  of  cattle  is  best  carried  on 
by  a  veterinarian  employed  by  the  municipality.  It  is  highly 
desirable  that  he  be  paid  well  enough  to  warrant  devoting  his 
time  exclusively  to  the  work  in  hand.  The  requirements  of 
the  work,  even  in  a  small  city,  call  for  the  undivided  attention 
of  one  man  for  milk  inspection  and  tuberculin  testing.  vThere 
should  be  a  decided  increase  in  the  budget  allotments  of  munic- 
ipalities for  the  proper  enforcement  of  tuberculin  test  ordi- 
nances, f  The  important  requirement  is  that  the  inspector 
should  noYbe  engaged  in  private  practice  and  consequently 
dependent  upon  the  good  will  of  the  dairymen.  The  customary 
system  of  paying  a  moderate  salary  for  a  portion  of  the  time- 
of  a  practicing  veterinarian  is  detrimental  to  efficient  work  for 
the  municipality.  If  the  application  of  the  tuberculin  test  is 
made  optional  with  the  veterinarian,  the  test  will  certainly  not 
be  made.  The  veterinarian  can  not  do  his  full  duty  without 


76      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

giving  offense  that  will  eventually  destroy  his  practice.  Private 
practice  and  efficient  municipal  work  are  incompatible. 

The  man  carrying  on  the  testing  must  be  proof  against  the 
corruption  to  which  he  will  be  continually  exposed.  His  pro- 
fessional skill  and  judgment  will  be  criticized  by  the  dairy- 
men and  by  jealous  unprofessional  aspirants  for  his  '  'job. ' '  The 
officials  or  board  to  whom  he  is  responsible  must  entertain 
unswerving  faith  in  his  qualifications,  else  they  will  waver  in 
the  face  of  the  storm  of  protest  and  denunciation  that  will 
emanate  from  the  dairymen. 

Test  by  any  licensed  veterinarian.  In  some  of  the  larger 
municipalities  the  ordinance  may  require  the  dairyman  to  pro- 
duce a  report  from  any  qualified  veterinarian,  but  such  a  pro- 
vision is  an  invitation  to  fraud  and  dishonesty.  Under  such 
conditions  the  effectiveness  of  a  tuberculin  test  ordinance  is 
likely  to  be  entirely  destroyed. 

In  Berkeley,  Cal.,  an  ordinance  was  passed  (Appendix  A) 
permitting  any  licensed  veterinarian  to  make  tuberculin  tests, 
but  containing  provision  for  subsequent  tests  by  the  repre- 
sentative of  the  health  officer  in  case  the  latter  doubted  the 
accuracy  of  the  reports.  That  this  feature  was  undesirable 
was  fully  recognized  but  it  would  have  been  quite  out  of  the 
question  to  have  obtained  the  appointment  of  a  city  veteri- 
narian to  do  all  the  work.  The  first  attempt  to  exercise  the 
provision  in  regard  to  retesting  resulted  in  litigation  and  the 
invalidation  of  the  ordinance  on  a  legal  technicality  not  con- 
cerning the  test. 

The  Chicago  tuberculin  test  ordinance  is  weak  on  this  point, 
for  in  the  rules  regarding  the  tuberculin  testing  of  cows  any 
licensed  graduate  veterinarian  is  permitted  to  do  the  work 
(Appendix  B).  The  Duluth  ordinance  is  stronger  in  this  fea- 
ture (Appendix  C). 

Milk  contracts.  In  the  larger  cities  most  of  the  retailers 
are  supplied  by  the  producers  or  others,  under  the  terms  of 
yearly  contracts.  Unless  the  health  regulations  have  been  very 
rigidly  enforced,  these  contracts  are  not  liable  to  contain 
clauses  providing  that  the  milk  conform  to  health  require- 
ments. Any  radical  or  sudden  change  in  the  law  is  apt  to 


APPLICATION  OF  THE  TUBERCULIN  TEST.  77 

make  trouble  between  the  retailer  and  the  producer.  Due 
warning  obviates  the  difficulty. 

Application  of  the  tuberculin  test.  In  the  earlier  days  when 
the  tuberculin  test  was  in  the  experimental  stage,  it  was  cus- 
tomary to  take  a  series  of  normal  temperatures  of  the  cows 
during  the  whole  day  preceding  the  injection  of  tuberculin. 
The  data  thus  obtained  permitted  the  plotting  of  temperatures, 
before  and  after  injection,  in  a  most  convincing  way.  The  con- 
finement of  the  cows  for  the  day  for  taking  these  temperatures 
interferes  greatly  with  the  secretion  of  milk  and  entails  much 
extra  work.  These  circumstances  furnish  a  strong  incentive 
for  decreasing  the  number  of  these  "  normal  "  temperatures. 
In  practice,  veterinarians  take  about  two  temperatures  before 
injecting,  merely  to  establish  the  fact  that  the  animal  is  not  in 
a  febrile  condition. 

Temporary  numbers.  The  identification  of  the  cows  during 
the  test  is  satisfactorily  accomplished  by  painting  numbers  on 
the  rump  with  green  paint.  The  numbers  will,  in  a  few  cases, 
be  smudged  before  drying  and  the  difficulty  from  this  may  be 
obviated  by  numbering  all  the  cows  in  duplicate. 

Facilitating  observations  of  temperatures.  The  observation 
of  temperatures  may  be  expedited  by  the  use  of  several  ther- 
mometers simultaneously.  When  more  than  one  thermometer 
is  used  the  risk  of  breakage  necessitates  attaching  the  ther- 
mometer to  the  cow  by  a  string.  Special  ring  top  veterinary 
thermometers  on  the  market  facilitate  tying  a  string  to  the 
thermometer.  NThe  human  clinical  thermometer  may  have  a 
string  attached  to  it  through  the  medium  of  a  rubber  band 
firmly  wrapped  around  the  top.  There  is  attached  to  the  other 
end  of  a  six-inch  string  a  pair  of  dog-tooth  clasps.  When  the 
thermometer  is  inserted  in  the  rectum,  the  clasp  is  attached 
either  to  a  firm  concretion  of  manure  on  the  hair  or  to  the 
skin,  which  latter  however  is  liable  to  cause  kicking. 

Nervous  cows  will  greatly  delay  the  work  by  resisting  the  in- 
sertion of  the  thermometer.  This  may  be  obviated  by  enlisting 
the  services  of  one  of  the  milkers  to  stand  at  one  side  and  pat  the 
cow  on  the  back.  Quiet,  businesslike  work,  with  the  minimum 
of  delay  and  excitement  of  the  cow,  must  always  be  kept  in  mind. 


78      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

The  services  of  at  least  one  non-professional  assistant,  besides 
the  stable-man,  will  be  found  very  useful.  He  could  be 
employed  to  insert  thermometers  and  to  record  the  tempera- 
tures on  the  blank  provided  for  the  purpose.  The  responsible 
work  of  reading  the  thermometers  can  thus  becarried  on 
rapidly  by  the  veterinarian  making  the  test.  V^FTg.  10  shows  a 


Herd  of..     L^t**, 


Location 

(J 

Injected    .    ^.PA 


Test  by  fa  ft  J{ 


•  Temperatures  Q  ^ 

.         After        Yf  /HV  • 


A3 


A3 


1.2 


1.1 


1.  1 


1,2 


2.1 


a* 


6,4 


0 


S 


/*V«".  /*v.     Blank  for  recording  temperatures. 

convenient  blank  for  recording  temperatures.  It  will  be  noted 
that  the  temperatures  are  written  in  an  abbreviated  form.  For 
instance  101.6°  is  recorded  as  1.6,  etc.  The  blank  as  used  is 
three  inches  broad  and  about  seven  inches  long.  The  width 
permits  folding  the  records  and  filing  them  away  with  the 
identification  cards  mentioned  on  page  81.  The  significance  of 
the  numbers  in  the  column  at  the  extreme  right  is  described 
^n  page  82. 

After  the  temperature  is  read,  the  thermometer  is  inserted  in 
a  pot  of  vaseline  until  needed  for  use  next  time.  If  there  is 
no  convenient  ledge  at  the  rear  of  the  cows,  a  light  portable 
box,  about  a  yard  high,  forms  a  convenient  stand  for  the  vas- 
eline and  thermometers. 


APPLICATION  OF  THE  TUBERCULIN  TEST.  79 

Injection  with  tuberculin.  The  tuberculin  is  injected  during 
the  evening  at  a  time  to  allow  an  interval  of  ten  hours  before 
the  cows  are  milked  the  next  morning.  The  insertion  of  the 
hypodermic  needle  is  accomplished  with  greatest  facility  and 
least  danger  to  the  operator  by  leaning  on  the  withers  of  the 
cow  and  injecting  upon  the  side  opposite  to  the  operator. 
Asepsis  is  practically  accomplished  by  dipping  the  needle  in 
concentrated  carbolic  acid  each  time  before  use. 

Temperatures  after  injection.  Temperatures  are  taken  every 
two  hours  from  the  10th  to  the  16th  hours,  and  later  in  the 
case  of  those  animals  showing  an  elevation  to  103.5°  at  the 
16th  hour.  It  is  frequently  recommended  that  the  tempera- 
tures be  taken  from  the  8th  to  the  20th  hour.  Such  require- 
ments impose  serious  h'ardship  on  the  dairyman  by  the  loss  of 
milk,  due  to  the  annoyance  of  the  cows.  For  all  practical 
purposes  the  shorter  period  of  taking  temperatures  is  sufficient 
to  reveal  a  reaction.  The  animals  should  be  under  as  quiet 
and  natural  conditions  as  possible  during  the  test.  It  is  usually 
desirable  to  allow  them  liberty,  with  access  to  drinking  water, 
between  the  12th  and  14th  hours. 

Interpretation  of  temperatures.  A  rise  of  1.5°F.  above  the 
normal,  if  gradual  and  distributed  over  a  period  of  several 
hours,  followed  by  a  gradual  decrease,  constitutes  a  reaction. 
Fig.  10  shows  two  typical  tuberculin  reactions.  A  brief 
upward  fluctuation  of  the  temperature  is  not  regarded  as  sig- 
nificant. In  the  case  of  the  ordinary  well  marked  reactions, 
it  is  not  considered  necessary  to  continue  taking  temperatures 
after  the  fastigium  has  been  passed.  Animals  exhibiting  ques- 
tionable reactions  should  be  retested  one  month  later,  injected 
with  three  times  the  usual  dose  of  tuberculin. 

It  is  the  rule  not  to  condemn  animals  showing  a  rise  of  tem- 
perature when  in  oestrum  or  when  within  six  weeks  of  par- 
turition. It  is  well  to  inject  all  such  animals  in  a  herd  and  to 
retest  later  those  exhibiting  a  fever. 

Limitations  of  tuberculin  test.  The  tuberculin  test  does  not 
reveal  facts  concerning  the  extent  of  disease.  Hence  in  a  small 
percentage  of  reacting  cases  no  lesions  can  be  found  in  post- 
mortem, probably  due  to  the  fact  that  the  lesion  is  too  small 


80      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 


to  detect.  Animals  in  the  advanced  stages  sometimes  fail  to 
react  but  the  existence  of  tuberculosis  in  such  cases  should  be 
readily  detected  from  the  physical  appearance  of  the  animal. 
There  are  at  least  two  conditions  under  which  an  animal  once 
failing  to  react  may  at  a  later  time  react  to  the  test.  During 
the  incubation  period  of  the  disease,  that  is,  when  the  tubercle 
bacilli  are  within  the  body  but  before  a  lesion  is  developed,  no 
reaction  will  occur.  Later,  the  animal  will  respond.  Thor- 
oughly encapsulated  lesions  will  not  permit  response  to  tuber- 
culin, but  later  may  become  active  and  cause  reaction.  These 
facts  are  of  great  significance  in  pointing  to  the  necessity  of 
frequent  testing. 

Fraud.  Dishonesty  on  the  part  of  the  attendants  of  the 
cattle  may  be  responsible  for  erroneous  results  of  a  test.  It  is 
an  important  fact  that  a  tubercular  animal  will  not  give  two 
reactions  in  succession.  Thus  a  dairyman  may  inject  his  herd 
a  few  days  previous  to  an  unwelcome  expected  test,  and  there- 
by wholly  mislead  the  man  making  the  later  test.  Tuberculin 
is  readily  purchased  upon  the  market  but  its  sale  should  be 
subject  to  restrictions.  Febrifuge  drugs  are  said  to  be  also 
used  to  defeat  the  tuberculin  test,  by  counteracting  the  febrile 
conditions.  Frauds  may  be  extensively  practiced,  but  unex- 
pected tests  will  eventually  expose  the  dishonest  practice. 

fmanent  identification  of  animals.     The  thorough  identifi- 
cation' of  the    animals  is  under  most    conditions  a  necessary 

matter.  The  liability  of  fraud 
is  very  great  when  any  com- 
pulsion attends  the  application 
of  the  test  or  the  subsequent 
disposition  of  the  reacting  ani- 
mals. A  useful  means  of  iden- 
tification is  afforded  by  metal 
ear-tags,  numbered  serially 
and  bearing  a  legend  identify- 
ing the  official  body  respon- 
sible for  the  test,  as  for  in- 
stance, a 'board  of  health  or 
a  milk  commission.  Fig.  11 


Fig.  11. 
cattle. 


Ear-tag  Jor 


APPLICATION  OF  THE  TUBERCULIN  TEST. 


81 


shows  ear-tags  as  described.  The  characters  borne  by  the  tag 
are  .stamped  on  at  the  factory  and  consequently  may  not  be 
readily  imitated  for  fraudulent  purposes.  Furthermore,  dupli- 
cation of  numbers  will  not  occur.  The  ear-tags  should  be 
affixed  after  a  test  to  all  animals  whether  they  have  reacted 
or  not.  It  is  of  no  particular  value  to  tag  only  non-reactors, 
since  after  subsequent  exposure  of  the  animal  to  infection  the 
tag  gives  no  guarantee  of  freedom  from  tuberculosis.  In  one 
case  where  such  a  practice  was  in  vogue,  it  was  observed  that 
dairymen  would  willingly  purchase  a  tagged  cow  without  fur- 
ther guarantee  of  health.  Furthermore,  owners  have  pointed 
out  the  death  from  tuberculosis  of  a  tagged  animal  as  an  evi- 
dence of  the  unreliability  of  the  test.  It  is  not  well  to  encour- 
age the  idea  that  an  ear-tag  is  a  fetish  against  tubercular  infec- 
tion. It  is  quite  possible  that  ear-tags  may  be  lost  and  also 
that  ear-tags  may  be  transferred  to  other  animals  for  fraudulent 
purposes.  An  absolutely  safe  identification,  then,  requires  fur- 
ther safeguards.  For  this  purpose  the  writer  devised  a  3  by 
5-inch  card  printed  with  the  outline  of  a  cow  and  blanks  for 
important  data  (53). 


Label  No. 


Breed 


Own* 


Test  No. 


Fig.  12.     Card  employed  by  the  writer  for  the  identification  of  cows. 


82      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

Fig.  12  shows  such  a  card  filled  out  with  descriptive  matter, 
etc.  The  amount  of  sketching  required  is  very  small.  The 
color  of  the  animal,  together  with  some  distinctive  peculiarity, 
may  be  all  that  is  necessary  to  record  for  purposes  of  identifi- 
cation. Mutilations  of  the  ears  or  the  character  and  location 
of  brands  may  be  readily  indicated  by  a  stroke  of  the  pencil. 
The  insertion  of  the  temporary  and  permanent  numbers  on 
both  the  card  and  the  temperature  blank  makes  it  possible  to 
keep  an  accurate  record  of  the  test  history  of  every  cow  in  a 
herd.  Such  cards  are  carefully  filed  for  use  in  subsequent 
inspection  of  the  herd.  For  instance,  when  rules  or  ordi- 
nances require  the  testing  of  all  animals  admitted  to  a  herd, 
the  identification  system  gives  the  inspector  full  knowledge  of 
the  facts.  The  presence  of  a  condemned  animal,  minus  the 
ear-tag,  could  be  proven  by  comparison  of  the  markings  of  the 
cow  with  the  sketches.  Moak  has  devised  a  .slight  modification 
of  the  identification  card  as  shown  in  Fig.  13.  He  is  enabled 
to  file  away  the  tuberculin  test  record  on  the  card,  which  is 
a  feature  particularly  useful  when  a  few  cows  are  tested  at  a 
time. 

Disposal  of  tubercular  animals.  In  some  states  it  may  be 
possible  for  dairymen  to  take  advantage  of  partial  indemnifica- 
tion offered  by  the  state  to  the  owners  of  condemned  animals. 
n  the  early  days  of  effort  to  exterminate  bovine  tuberculosis, 

any  states  adopted  a  policy  of  at  least  partially  indemnifying 
the  owner  for  losses  sustained  in  destroying  animals.  This 
method  in  general  failed  to  accomplish  permanent  benefit, 
because  sufficient  funds  were  not  appropriated  to  make  the 
work  as  thorough  as  the  circumstances  demanded.  The  right 
of  an  owner  of  a  tubercular  animal  to  demand  indemnification 
for  the  loss  occasioned  by  its  slaughter  on  the  ground  of  the 
benefit  to  the  public  health,  seems  to  be  an  open  question. 
The  principle  certainly  is  not  recognized  when  carcasses  are 
condemned  in  abattoirs  nor  is  a  man  in  quarantine  for  the  pub- 
lic good  compensated  therefor.  The  owner  of  a  herd,  in  tol- 
erating the  existence  of  the  disease,  is  quite  as  responsible  for 
the  losses  from  it  as  is  the  public.  The  practice  of  indemnifica- 
tion certainly  facilitates  work  in  combating  tuberculosis. 


•n  O  2 


•n  o  2 


2     O 

7>     > 


-22        3 

O 


•n  o  2 


-no   2 


BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

fit  is  the  purpose  here  merely  to  allude  to  the  matter  of 
control  of  bovine  tuberculosis.  '  When  municipalities  interfere 
with  dairymen  in  the  tuberculosis  matter,  the  cry  is  usually 
raised  that  nothing  should  be  done  until  indemnification  is 
available.  Under  the  conditions  ordinarily  imposed  by  a  city 
ordinance,  such  a  claim  is  absurd. 

\  The  slaughter-house  always  offers  an  opportunity  for  the  dis- 
posal of  tubercular  animals.  The  regulations  of  the  Bureau 
of  Animal  Industry  of  the  United  States  Department  of  Agri- 
culture  permit  the  veterinary  inspectors  to  pass  certain  slightly 
*-)  diseased  carcasses  as  fit  for  human  food.  In  most  of  our  abat- 
toirs there  is  no  inspection  of  meat  by  Federal  or  local  author- 
ities, consequently  we  consume  regularly  the  flesh  of  broken- 
down  tubercular  dairy  cows.  In  view  of  this,  the  slaughter  of 
slightly  diseased  cows  that  have  merely  reacted  to  the  test, 
cannot  be  regarded  as  especially  disgusting.  The  slaughter  of 
reacting  cows  does  not  afford  a  great  loss  to  the  dairyman,  for 
at  certain  seasons  of  the  year  there  is  not  a  wide  margin  of 
difference  between  the  beef  and  the  dairy  value  of  a  scrub  cow. 
k--ft""iSDy  no  means  a  simple  matter  to  enforce  the  clauses  of 
ah  ordinance  requiring  that  reacting  animals  be  permanently 
removed  from  the  herd.  Unfortunately  it  is  quite  necessary 
to  assume  that  condemned  cows  may  be  returned  to  the  herd 
by  stealth.  Thorough  inspections,  with  the  aid  of  the  identifi- 
cation system,  will  quite  prevent  the  general  practice  of  such 
fraud.  An  instance  has  come  to  notice  where  the  owner  was  so 
deaf  to  warning  and  so  blind  to  the  truth  regarding  the  trans- 
missibility  of  tuberculosis  that  he  kept  the  reacting  cows  to 
suckle^dalry  calves. 

{stances  ari.se  in  which  the  dairyman,  having  dried  off  a 
number  of  reacting  cows,  keeps  them  at  pasture  a  year  and 
submits  them  for  a  retest  later.  In  general  such  animals  will 
continue  to  react  from  year  to  year,  although  some  may  cease 
to  react  because  of  the  encasulation  of  the  lesions.  Such 
animals  unless  very  closely  supervised,  are  not  desirable  in  a 
herd  free  from  tuberculosis.  There  is,  furthermore,  the  great 
probability  that  the  owner  will  tamper  with  the  reacting  cows 
by  surreptitiously  injecting  them  with  tuberculin  with  the 


^ 


EDUCATION  OF  DAIRYMEN.  85 

purpose  of  deceiving  the  veterinarian  testing  them  in  good 
faith.     The  rule,  "once  condemned,  always  condemned,"  is 

.     safest  to  follow. 

Disinfection.  The  disinfection  of  a  stable  after  the  reacting 
v  __  animals  have  been  removed  is  a  matter  that  most  vitally  con- 
cerns the  dairyman  and  he  might  be  expected  to  do  this  work. 
In  practice,  though,  it  will  be  found  that  the  dairyman  will 
not  do  the  work  thoroughly  or  may  neglect  it  entirely.  It  is 
much  better  that  it  be  done  under  the  supervision  of  the  veter- 
inarian making  the  test. 

A  thorough  cleaning  of  the  stable  is  a  prerequisite  to  the  use 
^of  the  disinfectant  and  should  be  carried  out  with  such 
thoroughness  that  no  manure  remains  anywhere.  Mercuric 
chloride  is  a  good  disinfectant  for  use  in  the  stable.  It  is  made 
up  in  the  proportion  of  1  ounce  to  8  gallons  of  water  and 
should  be  mixed  in  a  wooden  tub  or  barrel.  The  mercuric 
chloride  is  best  brought  into  solution  in  a  small  quantity  of 
hot  water  and  then  diluted  with  the  whole  amount  of  cold 

"     water. 

On  account  of  the  danger  of  defacing  metal  work  about  the 
mangers  by  the  action  of  the  mercury,  it  may  be  well  to  use 
some  other  disinfectant  there.  A  5%  solution  of  carbolic  acid 
or  of  formalin  may  be  used  (8). 

Education  of  dairymen  concerning  bovine  tuberculosis.  The 
regulations  against  bovine  tuberculosis  in  the  interest  of  the 
public  health  and  without  the  alternative  of  pasteurization  must 
eventually  result  in  either  driving  the  dairymen  into  completely 
subjugating  the  disease  in  their  herds,  or  in  the  abandonment 
of  the  ordinance.  Ignorance  or  skepticism  or  false  economy 
will  induce  quite  a  percentage  of  dairymen  to  violate  the  prin- 
ciples necessary  for  the  control  of  bovine  tuberculosis,  in  spite 
of  a  tuberculin  test  ordinance.  The  business  can  not  stand 
such  a  drain,  and  rigid  enforcement  inevitably  results  in  driving 
the  unfit  out  of  business.  The  intermittent  way  in  which 
tuberculin  test  ordinances  have  been  enforced  always  lends 
hope  that  interference  will  be  but  temporary.  The  ultimate 
triumph  of  a  tuberculin  test  ordinance  is  impossible  unless  the 
dairymen  are  educated  and  converted  on  the  subject  of  bovine 


86      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

tuberculosis.      To   this  end,   the   dairymen   supplying  a   city 

should  all  be  supplied   with  circulars  of  information  dealing 

with  the  problem  of  the  control  of  bovine  tuberculosis.      In  a 

large  number  of  states,   assistance  in  preparing  such  circulars 

may  be  had  from  state  veterinary  sanitary  officials,  veterinarians 

^^agricultural  experiment  stations,  and  also  from  the  Bureau 

~4>  of  Animal  Industry  at  Washington. 

Anthrax.  This  cattle  disease  is  certainly  transmissible  to 
man  by  inoculation,  but  the  writer  has  not  encountered  a  report 
of  a  case  where  the  infection  has  been  borne  by  milk. 

The  disease  appears  among  cattle  during  warm  weather  in 
certain  localities.  Its  onset  is  so  abrupt  and  death  usually 
occurs  with  such  suddenness  that  there  is  little  likelihood  of  a 
diseased  animal's  transmitting  the  disease  through  the  milk. 
During  an  outbreak  of  anthrax  it  might  be  enough  from  the 
public  health  standpoint  to  insist  that  no  cows  with  a  fever  be 
allowed  in  the  dairy.  Even  such  a  requirement  would  ordin- 
arily be  superfluous,  for  a  cow  with  a  high  fever  due  to  anthrax 
would  not  yield  milk. 

Suppuration.  Marked  examples  of  suppuration  warrant  the 
temporary  rejection  of  the  milk  of  a  cow.  Dehorning,  or  the 
accidental  loss  of  a  horn,  is  quite  apt  to  lead  to  infection  of 
the  frontal  sinuses,  and  if  the  discharge  is  not  properly  re- 
moved it  creates  a  disgusting  stench.  For  this  reason  dehorn- 
ing is  preferably  done  \vhen  a  cow  is  dry.  Open  suppurating 
actinomycotic  lesions  are  objectionable.  Small  abscesses  occur 
on  the  backs  of  cows,  due  to  the  presence  of  larvae,  Hypodenua 
bovis,  or  H.  lineaia,  popularly  called  warbles.  Trouble  is  best 
prevented  by  squeezing  out  the  larvae  when  small.  Suppur- 
ation about  the  udder  is  especially  objectionable.  Mammitis 
(garget)  furnishes  good  reason  for  excluding  the  milk  of  the 
cow  from  sale,  even  if  only  one  quarter  of  the  udder  is  involved. 
Since  garget  is  caused  by  streptococci,  all  sorts  of  streptococcus 
infections  in  man  have  been  attributed  to  the  use  of  milk  con- 
taining streptococci.  Such  transmission  of  infection  is  possible 
and  probable,  but  difficult  to  prove.  The  subject  is  further 
discussed  in  Chap.  VII. 


MALTA  FEVER.  87 

Cowpox.  This  eruptive  disorder  of  the  skin  of  the  udder  is 
very  common  and  terminates  in  ulcers  and  frequently  in  ab- 
scesses. At  times  it  would  be  a  very  serious  matter  to  demand 
the  rejection  of  the  milk  of  all  cows  showing  small  areas  of 
infection.  The  very  common  practice  of  using  carbolized 
vaseline  on  the  lesions  practically  prevents  danger  of  trans- 
mitting infection  from  these  areas  when  not  on  the  teats. 
Regulations  on  the  subject  might  well  allow  the  use  of  milk 
when  the  udder  only  is  involved  and  under  treatment,  and 
exclude  cases  showing  open  abscesses  or  involvement  of  the 
teat.  The  writer  is  not  familiar  with  reports  of  cases  where 
the  transmission  of  this  disease  through  the  milk  has  been 
proven.  The  fact  that  vaccination  against  smallpox  is  largely 
practiced  has  been  noted  in  connection  with  the  subject. 

Parturition  disturbances.  There  is  a  general  consensus  of 
opinion  that  the  milk  of  a  cow  for  about  a  week  after  calving 
(colostrum)  has  an  unusual  composition  and  is  unwholesome 
for  human  consumption.  '  The  Federal  standard  sets  this  period 
at  ten  days,  and  likewise  prohibits  the  use  of  milk  for  fifteen 
days  before  calving  (Chap.  X).  Besides,  during  this  time 
the  udder  is  more  or  less  inflamed  in  consequence  of  the  resump- 
tion of  function.  Cases  exhibiting  retained  placenta,  metritis, 
etc.,  should  not  be  allowed  in  the  milking  herd. 

Malta  fever.  This  disease,  prevalent  on  the  island  of  Malta 
and  elsewhere,  chiefly  in  the  Mediterranean  region,  is  caused 
by  Micrococcus  melitensis.  Lately  it  has  been  determined  by  a 
commission  appointed  to  investigate  the  disease  that  it  is  prim- 
arily one  of  goats  and  is  transmitted  through  the  milk.  M. 
melitensis  may  be  found  in  the  milk  of  apparently  healthy  goats. 
The  blood  serum  of  such  animals  gives  a  positive  agglutination 
reaction  with  M.  melitensis,  and  that  of  other  goats  not  contain- 
ing the  germs  does  not.  The  test  has  led  to  the  conclusion 
that  41%  of  the  goats  in  Malta  are  infected.  Ten  per  cent,  of 
them  have  the  germs  in  the  milk.  In  1905  a  very  conclusive 
demonstration  of  the  relation  of  goats  to  the  disease  was 
afforded  by  the  shipment  of  a  number  of  goats  from  Malta  to 
the  United  States.  The  milk  was  used  by  the  crew  of  the  ship 
with  the  result  that  a  number  of  men  contracted  Malta  fever. 
The  imported  animals  were  slaughtered  (2). 


88      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

Foot  and  mouth  disease.  This  highly  contagious  disease  of 
cattle  is  transmissible  to  man  through  the  milk  (24).  The 
symptoms  in  cattle  consist  of  eruption  of  vesicles  in  the  mouth, 
around  the  coronet,  between  the  toes  and  on  the  udder,  accom- 
panied by  a  rise  of  temperature.  The  mortality  is  not  high, 
but  great  losses  are  incurred  by  the  diminution  of  the  milk  flow 
due  to  the  fever  and  to  the  starvation  caused  by  the  mouth 
lesions.  Mycotic  stomatitis,  which  occurs  occasionally  on  the 
Pacific  coast  and  elsewhere,  is  liable  to  be  confused  with  foot 
and  mouth  disease  (18).  This  last  mentioned  disease  is  com- 
mon in  Europe  but  is  not  permanently  implanted  in  the  United 
States.  It  has  been  introduced  several  times  and  successfully 
eradicated.  At  the  time  of  writing,  the  existence  of  the  dis- 
ease has  been  discovered  in  certain  areas  of  Pennsylvania,  Mich- 
igan and  New  York. 

Milk-sickness.  In  the  early  days  of  the  settlement  of  the 
central  portion  of  the  United  States,  cases  of  illness  attributed 
to  consuming  milk  of  diseased  cattle  were  not  uncommon  (16). 
The  symptoms  in  cattle  and  in  man  are  quite  definite.  Fifty 
years  ago  the  disease  had  a  distinct  standing  in  medicine  but 
of  late  years  it  has  been  all  but  forgotten,  due  to  its  present 
rarity.  Jordan  and  Harris  (ll)  have  recently  discovered  a 
focus  of  infection  in  the  valley  of  the  Pecos  River,  N.  M., 
which  gave  them  opportunity  to  study  cases  in  both  cattle  and 
man.  In  man  the  symptoms,  among  others,  included  vomiting, 
constipation,  and  great  prostration.  They  noted  the  sweetish 
odor  of  the  breath  described  in  the  old  literature.  Affected 
cattle  in  the  early  stages  appeared  weak  and  exhibited  a  shuf- 
fling gait,  accelerated  breathing,  and  sometimes  trembled  and 
fell.  In  advanced  stages  the  animal  lay  with  the  head  to  one 
side  as  in  milk  fever,  but  continued  to  tremble.  Post-mortem 
examination  with  bacteriological  examination  did  not  result  in 
the  identification  of  any  of  the  well-known  cattle  diseases.  An 
organism  called  by  them  B.  lactinwrbi  was  regarded  as  the 
cause  of  the  disease. 


REFERENCES.  89 

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90      BOVINE  TUBERCULOSIS  AND  OTHER  CATTLE  DISEASES. 

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46.  SCHROEDER  and  MOHI^ER.     The  tuberculin  test  of  hogs  and  some 
methods  of  their'infection  with  tuberculosis.     Bui.  No.  88,  Bur.  Anim. 
Ind.,  f\  S.  Dept.  Agr.,  Washington,  D.  C.,  1906. 

.  47.  SMITH.  A  comparative  study  of  bovine  tubercle  bacilli  and  of 
human  bacilli  from  sputum.  Jour.  E.rper.  Med.,  Vol.  Ill,  1898,  Nos. 
4  and  5. 

48.     SMITH.     Studies  in  mammalian  tubercle  bacilli  (III).    Jour.  Med. 
Research,  N:  S.,  Vol.  VIII,  1905,  p.  253. 


92      BOVINE  TUBERCULOSIS  AND  OTHER  ANIMAL  DISEASES. 

49.  SMITH.     The  channels  of  infection  in  tuberculosis,  together  with 
some  remarks  on  the  outlook  for  a  specific  therapy.     Trans.  Mass.  Med. 
Soc.  for  1907. 

50.  SMITH.     The  bovine  and  the  human  type.      Jour.  Amer.  Med. 
Assoc.,  Vol.  U,  1908,  No.  15,  p.  1258.     (A  journal  abstract.) 

51.  Sous-CoHEN.  Bacteriological  examination  of  the  feces  as  a  means 
of  early  diagnosis  in  tuberculosis.  'Transactions  Third  Annual  Meeting 
of  the  National  Association  for  the  Study  and  Prevention  of  Tubercu- 
losis, p.  228. 

52.  VON  BEHRING.     The  suppression  of  tuberculosis,  etc.    New  York  : 
J.  Wiley  &  Sons. 

53.  WARD.     The  identification  of  cows.     The  Cornell  Countryman, 
Vol.  Ill,  1906,  No.  5,  p.  110. 

54.  WARD  and  HARING.     Bovine  tuberculosis.     Bui.  No.  199,  Univ. 
of  Cal,  Agr.  Exp.  Sta.,  Berkeley,  Cal.,  1908. 

55.  WARD  and  HARING.     The  prevalence  of  tuberculosis  among  dairy 
cattle  in  the  vicinity  of  San  Francisco',  California.     Trans.  Sixth  Intern. 
Cong,  on  Tuberculosis,  Washington,  D.  C.,  1908. 

56.  WHITE  and   McCAMPBELL.      The  ophthalmo-tuberculin  test  in 
cattle.     Trans.  Sixth  Intern.  Cong,  on  Tuberculosis,  Washington,  1908. 


CHAPTER  V. 


MUNICIPAL  SANITARY  CONTROL  OF  MILK. 


Control  of  milk  supply.  The  dairy  business  is  generally 
regulated  by  a  licensing  system.  Municipal  ordinances  define 
the  qualities  required  in  the  milk  sold,  and  specify  certain 
methods  that  shall  or  shall  not  be  practiced  in  its  production. 
The  issuing  of  a  license  to  sell  the  milk  may  be  made  condi- 
tional upon  the  compliance  with  certain  demands.  The  desired 
standard  may  be  maintained  by  a  system  of  frequent  renewal 
of  license,  by  provisions  for  the  revocation  of  license,  or' by  the 
exaction  of  other  penalties  through  the  courts. 

Inspection.  Knowledge  of  the  requirements  of  municipal 
milk  inspection  and  of  methods  of  accomplishing  desired  results 
has  been  increasing  very  rapidly  of  late.  A  particularly  care- 
ful and  exhaustive  study  of  present  conditions  and  remedial 
measures  has  recently  been  made  in  Washington  by  a  Confer- 
ence appointed  by  the  Commissioners  of  the  District  of  Col- 
umbia (3).  The  report  of  that  conference  with  accompanying 
papers  is  a  valuable  guide  for  shaping  new  legislation  on  milk 
sanitation.  The  organization,  administrative  methods  and 
legal  features  of  municipal  milk  inspection  in  Washington 
have  been  described  by  Woodward  (18-). 

The  inspection  of  equipment  of  the  establishments  and  the 
methods  of  handling  milk  constitutes  an  important  part  of  any 
municipal  milk  inspection  service.  In  actual  practice,  the 
inspector  will  fall  far  short  of  accomplishing  the  best  results 
unless  he  becomes  an  instructor  in  dairy  practice,  as  well  as 
an  agent  to  detect  violations  of  law.  He  must  point  out  on 
the  spot  defects  and  ways  of  improvement,  which,  if  not  carried 
out,  may  be  made  occasion  for  prosecution.  He  must  also 
furnish  a  comprehensive  report  to  his  superior  officer  in  regard 
to  existing  conditions. 


94  MUNICIPAL  SANITARY  CONTROL  OK  MILK. 

The  dairy  score  card.  The  dairy  score  card  has  been  found 
a  most  useful  means  for  simplifying  the  work  of  dairy  inspec- 
tion. The  system  is  adapted  from  a  method  used  to  score  the 
conformation  of  cows,  etc.  All  of  the  essential  facts  of  im- 
portance regarding  equipment  and  methods  are  tabulated  in  an 
orderly  manner,  and  numerical  weight  is  assigned  to  each  point 
in  proportion  to  its  importance.  The  inspector  takes  up  each 
point  in  detail  and  enters  on  the  score  card  a  number  express- 
ing his  opinion  of  the  relation  that  the  condition  in  question 
bears  to  the  standard  of  perfection.  The  total  score  represents 
his  very  carefully  analyzed  opinion  of  the  condition  of  the 
dairy  as  compared  with  the  standard  of  perfection  followed. 

The  score  card  has  many  advantages.  The  tendency  to 
neglect  details  in  the  inspection  is  checked,  for  the  inspector 
has  before  him  comprehensive  suggestions.  If  he  is  inexper- 
ienced, any  tendency  to  overestimate  or  underestimate  the 
importance  of  various  details  is  obviated.  In  making  recom- 
mendations regarding  certain  details  his  advice  is  made  more 
weighty  by  the  score  card,  to  which  he  may  refer  the  dairyman. 
A  copy  of  the  score,  left  with  the  dairyman,  is  a  permanent 
record  of  the  criticisms,  as  is  likewise  the  copy  kept  by  the 
inspector.  By  comparison  of  the  scores  made  at  different 
times  the  progress  of  improvement  maybe  measured. 

Inspection  with  scoring  can  most  readily  bring  about  the 
proper  equipment  of  dairies  in  the  matter  of  buildings  and 
equipment,  such  as  cooling  and  scalding  apparatus,  etc.  These 
features  are  necessary  and  desirable,  but  beyond  them  is  the 
problem  of  ensuring  the  practice  of  a  uniformly  thorough  asep- 
tic technic.  During  the  visits  of  the  inspector  some  idea  of 
the  technic  may  be  obtained  by  observation.  The  necessity 
for  haste  to  accomplish  results  in  some  cases  prevents  the  in- 
spector from  personally  observing  the  practice  of  all  the  details 
of  milk  handling.  Experience  in  observation,  supplemented 
by  cross-questioning,  enables  him  to  draw  out  information  on 
matters  that  he  may  not  have  time  to  wait  to  see.  In  any 
event,  there  are  long  periods  between  visits  when  the  methods 
are  not  under  control.  The  magnitude  of  dairy  inspection 
makes  it  difficult  to  have  these  visits  frequent  enough.  New 


INSPECTION.  95 

York  City  has  30  inspectors  to  look  after  thirty  or  forty  thous- 
and dairies  and  follow  the  product  to  the  consumer.  Only  15 
of  these  men  work  outside  of  the  city  (4).  Washington  is 
more  fortunate  with  960  dairies  for  6  inspectors  (18).  These 
men  visit  on  an  average  2.8  dairies  per  day. 

The  situation  in  these  cities  suggests  a  doubt  as  to  whether 
inspection  work  of  our  larger  cities  can  be  expanded  sufficiently 
to  bring  about  a  reform  in  the  methods  of  farm  laborers  ignor- 
ant of  aseptic  technic. 

The  following  score  card  is  one  adopted  by  the  Official  Dairy 
Instructors'  Association,  at  the  meeting  in  July,  1908.  This 
latest  modification  represents  the  consensus  of  opinion  of  the 
body  of  men  most  competent  to  judge  such  matters,  including 
in  its  membership  those  who  have  been  most  active  in  the 
introduction  of  the  score  card  and  most  experienced  in  its  use. 

UNITED  STATKvS  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAI,  INDUSTRY, 
DAIRY  DIVISION, 

SANITARY  INSPECTION  OF  DAIRIES. 


DAIRY  SCORE  CARD. 

Adopted  by  the  Official  Dairy  Instructors'  Association. 
(.Subject  to  revision  at  future  meeting's.) 

Owner  or  lessee  of  farm 

P.  O.  Address  ...  State 

Total  number  of  cows Number  milking. 

Gallons  of  milk  produced  daily 

Product  is  retailed  by  producer  in  : 

Sold  at  wholesale  to 

For  milk  supply  of 

Permit  No Date  of  inspection ,  190. 

REMARKS  ... 

(Signed)..... '. 

Inspector. 


OF 

UNIVERSITY 

Of 

£''-UK>RNl£, 


[Reverse. ~\ 


DETAILED   SCORE. 


EQUIPMENT. 

vSCORE. 

SCORE. 

Per- 
fect. 

Al- 
lowed 

METHODS. 

Per- 
fect. 

Al- 
lowed 

cows. 
Health 

6 

COWS  AND  STABLES. 

Cleanliness  of  cows  
Cleanliness  of  stables  
Floor  2 
Walls  1 
Ceiling  and  ledges  ] 
Mangers  and  partitions  1 
Windows                                            1 

8 
6 

6 
2 

2 

8 
9 

1 

•     2 

3 

2 

5 

3 
3 

l 

Apparently  in  good  health  1 
If  tested  with  tuberculin  once 
a  year  and  no  tuberculosis  is 
found,  or  if  tested  once  in 
six  months  and  all  reacting 
animals  removed  5 
(If  tested  only  once  a  year  and 
reacting    animals    found    and  re- 
moved, 2.) 
Comfort  
Bedding  1 
Temperature  of  stable  1 
Food  
Water  
Clean                                                1 

2 

2 
2 

4 
3 

3 

2 
4 

1 
1 

3 
1 
1 

1 

2 
2 

Stable  air 

Barnyard  clean  and  well  drained  . 
Removal  of  manure  daily  to  field 
or  proper  pit  
(To  50  feet  from  stable,  1.) 

UTENSILS  AND  MILKING. 

Care  and  cleanliness  of  utensils  .... 
Thoroughly  cleansed  5 
Inverted  in  pure  air  3 
Cleanliness  of  milking  
Clean,  dry  hands                            3 

Fresh.  1 
Light:  Foursq.  ft.  of  glass  per  cow 
(3sq.  ft.,3;  2  sq.  ft.,  2;  1  sq.  ft.,1. 
Deduct  for  uneven  distribution.) 
Ventilation  :  Automatic  system  
(Adjustable  windows,  1.) 
Cubic  feet  of  space  for  cow:  500 
to  1000  feet   
(Less  than  500  feet,  2  ;  less  than 
400  feet,  1  ;  less  than  300  feet,  0.) 

STABLES. 

Location  of  stable 

Udders  washed  and  dried  6 
(Udders  cleaned  with  moist  cloth, 
4  ;  cleaned  with  dry  cloth  at  least 
15  minutes  before  milking,  1.) 

HANDLING  THE  MILK. 

Cleanliness  of  attendants  
Milk  removed  immediately  from 
stable  
Cleanliness  of  milk  room  
Prompt  cooling.    (Cooled  imme- 
diately after  milking  each  cow) 
Efficient  cooling  ;  below  50°  F  
(51°  to  55°,  4  :  56°  to  60°,  2.) 
Storage;  below  50°  F.... 
(51°  to  55°,  2;  56°  to  60°,  1.) 
Transportation  ;  iced...  
(For  jacket  or   wet   blanket   al- 
ow 2  ;    dry    blanket    or    covered 
wagon,  1.) 

Total  

Well  drained.  1 
Free  from  contaminating  sur- 
roundings    1 
Construction  of  stable  
Tight,  sound  floor  and  proper 
gutter  2 
Smooth,  tight  walls  and  ceiling  1 
Proper  stall,  tie,  and  manger.  1 

UTENSILS. 

Construction  of  utensils  



Water  for  cleaning  
(Clean,  convenient,  abundant.) 
Small-top  milking  pail  
Facilities  for  hot  water  or  steam... 
Milk  cooler  .-. 
Clean  milking  suits  

HANDLING  THE  MILK. 

Location  of  milk  room  
Free  from  contaminating  sur- 
roundings    1 
Convenient  _v  1 
Construction  of  milk  room  
Floor,  walls,  and  ceiling  1 
Light,  ventilation,  screens  1 
Total  ... 

40 

60 

Score  for  equipment -+-  Score  for  methods. 


.    =:  Final  Score. 

NOTE  1. — If  any  filthy  condition  is  found,  particularly  dirty  utensils,  the  total  score  shall  be 
limited  to  49. 

NOTE  2.— If  the  water  is  exposed  to  dangerous  contamination  or  there  is  evidence  of  the  pres- 
ence of  a  dangerous  disease  in  animals  or  attendants,  the  score  shall  be  0. 


INSPECTION.  97 

The  score  card  eliminates  the  wide  variations  of  individual 
judgment  in  criticising  dairy  conditions.  There  .still  remains 
room  for  variations  between  the  work  of  different  inspectors. 
It  would  hardly  be  fair  to  compare  a  group  of  dairies  on  the 
basis  of  the  work  of  .several  inspectors.  Professor  R.  A.  Pearson 
has  introduced  a  scheme  to  eliminate  the  effect  of  variations  in 
individual  judgment.  The  inspectors  are  furnished  a  list  of 
questions,  the  answers  to  which  will  bring  out  the  actual  con- 
dition of  the  dairy.  The  answers  made  by  the  inspector  are 
placed  in  the  hands  of  an  expert  who,  in  his  office,  compiles 
the  facts  in  the  form  of  a  score.  Thus  the  work  of  a  number 
of  inspectors  may  be  unified  by  one  mind  and  the  quality  of 
uniformity  imparted  to  the  work  of  all.  The  system  is  being 
used  with  satisfaction  by  the  Boards  of  Health  of  Ithaca,  N.  Y., 
Geneva,  N.  Y.,  and  elsewhere.  l*he  blanks  used  are  repro- 
duced below.  The  description  of  what  constitutes  perfection 
under  each  heading  is  a  commendable  feature. 

DEPARTMENT  OF  DAIRY  INDUSTRY,  NEW  YORK  STATE  COLLEGE  OK 
AGRICULTURE. 

MILK  INSPECTION. 

Dairyman  .....     Date.. 

P.  ().  Location... 

No.  Cows  milking In  herd Ots.  Milk Cans  or  Bottles.... 

Milk  sold  to  License  No 

Report  by At  milking  time? Hour M. 

I.    Health  of  the  herd  and  its  protection. 
Do  all  cows  appear  healthy?.... 

Are  udders  sound  and  free  from  signs  of  disease? 

Are  cows  tuberculin  tested? 

Date  of  last  test...  .    Bv  whom.. 


Is  the  stable  well  built  to  protect  from  the  weather  ? 

Are  cows  brought  in  during  bad  storms? 

How  many  hours  are  the  cows  out  daily?.  . 
Width  of  stall ....  .    Length. . 


98  MUNICIPAL  SANITARY  CONTROL  OF  MILK. 

Is  the  stall  comfortable? How  are  the  cows  tied? 

Kind  and  quality  of  bedding 


Where  are  cows  kept  when  sick  and  at  calving  time? 


Is  the  stable  well  located? 


Number  and  size  of  windows 

Size  of  the  stable,  length width height 

How  ventilated?  ... 


Kinds  of  feeds  used 

Are  they  of  good  quality  and  proportions?.... 
Source  of  water  for  cows 
Method  of  watering 

II.     Cleanliness  of  the  con's  and  their  surrounding's. 

Are  the  cows  clean  ? How  are  they  cleaned? 

Is  the  hair  clipped  about  the  udder? 

Is  the  udder  cleaned  before  milking? How? When? 


Is  the  stable  free  from  accumulation  of  cobwebs,  dirt  and  dust? 

Is  the  stable  white-washed? 

Kinds  and  number  of  other  animals,  if  anv,  in  same  room  with  cows 


Same,  adjacent  rooms What  openings  between? 

Is  the  stable  protected  from  such  sources  of  contamination  as  privy, 

etc.  ? 

How  often  is  the  manure  removed  from  the  stable? 

Is  the  barnyard  free  from  manure  pile? And  mud  holes? 

Is  the  pasture  clean  and  free  from  injurious  plants? And  mud 

holes?..  . 


Is  the  stable  provided  with  dust-tight  ceiling? And  partitions? 


Is  feeding  done  before  or  after  milking? 

Is  the  floor  swept  or  dampened  before  milking? 

Is  the  air  free  from  dust  and  odors? 

III.    Construction  and  care  of  the  utensils. 

Are  all  utensils  such  that  they  can  be  thoroughly  cleaned? 

Method  of  washing  utensils? 

How  are  the  utensils  sterilized?  ... 


INSPECTION.  99 

Is  the  water  used  for  washing  utensils  pure?   ..  How  do  you 

know?.... 

What  is  its  source?  

Is  the  source  protected  against  contamination? 


How  are  utensils  cared  for  after  cleaning?  


Is  a  small-top  pail  used  for  milking? If  so,  what  style  and 

si/.e  of  opening? 

IV.    Health  of  employees  and  manner  of  milking. 

What  evidence  is  there  of  absence  of  contagious  disease  and  of  ex- 
posure of  family  and  employees  to  disease?  

Are  the  milkers  clean  personally? 

Do  the  milkers  wear  clean  over-all  suits? How  often  are 

the  over-alls  washed? 

Do  the  milkers  wash  their  hands  just  before  milking? 

Where? 
Do  milkers  have  wet  hands  when  milking? ,.... 


Are  milkers  careful  not  to  dislodge  hair  and  dirt  from  the  cow  while 

milking  ? 

Is  the  foremilk  discarded? 

V.    Handling  the  milk. 

How  is  the  milk  cooled? 

How  soon  after  milking  is  the  milk  cooled? 

To  what  temperature? 


Is  the  milk  handled  in  a  room  detached  from  the  stable? 

What  kind  of  floor? 

Is  the  milk  room  used  exclusively  for  milk,  and  is  it  free  from  dirt 

and  odors? 

At  what  temperature  is  the  milk  kept  after  cooling? 


How  is  milk  cared  for  during  transportation  to  market? 


DEPARTMENT  OF  DAIRY  INDUSTRY,  COLLEGE  OF  AGRICULTURE. 
CORNELL  UNIVERSITY. 

Score  Card  for  Production  of  Sanitary  Milk. 


Date 


Dairv  of 


P.  O. 


PER- 
FECT. 

SCORE. 

Remarks 

. 
Health  of  the 
herd  and 
its  protec- 

Health  and  comfort  of  the  cows  and 
their  isolation   when   sick   or  at 
calving-  time  
Location,  lighting  and  ventilation  of 
the  stable  
Food  and  water 

45 

35 
20 

Total  

100 

II. 

Cleanliness 
of  the  cows 
and  their 
surround- 

Cows   
Stable  
Barnyard  and  pasture  
Stable  air  (freedom   from   dust  and 
odors)  

30 
20 
20 

3d 

ings. 

Total  

100 

III. 

Construction   of    utensils    and   their 
cleaning-  and  sterilizing 

40 

Construction 
and  care  of 
the  uten- 

Water  supply  for  cleaning  and  loca- 
tion and  protection  of  its  source.:. 
Care  of  utensils  after  cleaning  
Use  of  small-top  milking  pail  

25 
20 
15 

SllS. 

Total  

100 

Health  of  employees 

45 

IV. 

Health  of  em- 

Clean over-all  milking  suits  and  milk- 
ing with  clean,  drv  hands 

30 

ployees  and 
manner  of 
milking 

Uuiet  milking,  attention   to  cleanli- 
ness of  the  udder  and  discarding 
foremilk..    

25 

Total 

100 

Prompt  and  efficient  cooling  

35 

V. 

Handling 

Handling  milk  in  a  sanitary  room 
and  holding  it  at  a  low  tempera- 
ture   

35 

the  milk. 

Protection  during  transportation  to' 
market  

30 

Total....  

100 

TOTAL  OF  ALL  SCORES  

500 

If  the  total  of  all  scores  is  And  each  division  is  The  sanitary  conditions  are 

480  or  above 90  or  above EXCELLENT 

450  or  above SO  or  above GOOD 

400  or  above 60  or  above MEDIUM 

Below  400 ....  Or  any  division  is  below  60....  ....POOR 


The  sanitary  conditions  are Scored  by 


INSPECTION.  101 

\  Reverse  J\ 

A  BRIKF  DKSCRIPTION  OF  WHAT  CONSTITUTES  PRRFRCT  UNDER  EACH 

HEADING. 


I.  Health.  No  evidence  of  chronic  or  infectious  disease  or  of  acute 
disease  in  any  member  of  the  herd  on  the  dairy  premises.  Free- 
dom from  tuberculosis  proven  by  the  tuberculin  te.st  made  within 
one  year. 

Comfort.  Protection  from  weather  extremes.  Stall  comfortable, — 
at  least  3  feet  wide  for  a  small  cow,  or  3^  feet  for  a  large  cow ; 
length  of  stall  sufficient  for  cow  to  rest  easily.  Sufficient  bedding. 
Frequent  out-door  exercise. 

Isolation.  Removal  of  cows  to  comfortable  quarters  outside  of  the 
dairy  stable,  when  sick  or  at  calving  time. 

Location  of  Stable.     Elevated,  with  healthful  surroundings. 

Lighting.  As  light  as  a  wrell  lighted  living  room,  and  with  not  less 
than  four  square  feet  for  light  from  the  east,  south  or  west,  for 
each  cow. 

Ventilation.  An  adequate  ventilating  system  of  the  King  or  other 
approved  pattern,  and,  except  when  the  stable  is  being  cleaned, 
no  marked  stable  odor. 

Food.     Clean,  wholesome  feeding  stuffs,  fed  in  proper  quantities. 

Water.  Clean,  fresh  water,  free  from  possibility  of  contamination 
by  disease  germs. 

I.I.  Cows.  Cleaned  by  thorough  brushing,  and  where  necessary  by 
washing;  no  dust  nor  dirt  on  the  hair  (stains  not  considered). 
The  udder  thoroughly  cleaned  by  brushing  at  least  thirty  minutes 
before  milking,  and  by  washing  just  before  milking,  leaving  the 
udder  damp  to  cause  dust  to  adhere. 

Stable.  Free  from  accumulation  of  dust  and  dirt  except  fresh  ma- 
nure in  the  gutter.  Apart  from  horses,  pigs,  privy,  poultry - 
house,  etc.  » 

Barnyard  and  Pasture.  No  injurious  plants,  no  mudhole  nor  pile 
of  manure  or  any  decaying  substance  where  cows  have  access. 

Stable  Air.  Free  from  floating  dust  and  odors.  Tight  partition  or 
floor  between  the  space  occupied  by  cows  and  that  used  for  storage 
of  feed  or  other  purpose. 

III.  Construction  of  Utensils.  Non-absorbent  material  and  every  part 
accessible  to  the  brush,  and,  except  inside  of  tubes,  visible  when 
being  cleaned. 


102  MUNICIPAL  SANITARY  CONTROL  OF  MILK. 

Cleaning.  Thorough  cleaning  with  brush  and  hot  water,  and  rins- 
ing. No  laundry  soap.  Thorough  sterilization. 

//  'ater,  from  a  source  known  to  be  pure  ;  protected  from  contamin- 
ation from  seepage,  or  surface  drainage. 

Care  of  ( 'tensils.  vSuch  as  to  avoid  contamination  by  dust  as  w7ell 
as  coarser  dirt. 

Small-top  /W/,-«-with  opening  not  over  seven  inches  in  diameter, 
and  at  lea.st  one-third  of  this  opening  protected  by  hood. 

IV.  Employees, — free   from  contagious  disease  and  not  dwelling  in  or 

frequenting  any  place  where  contagious  disease  exists. 

Milking  Suits, — freshly  laundered  and  clean  ;  ample  to  protect  from 
dust  and  dirt  from  the  milker's  person  or  clothing. 

Milker1  s  Hands.  Hands  and  teats  dry  when  milking.  Hands  thor- 
oughly cleaned  before  milking  each  cow. 

Milking  Quietly,—  so  as  to  avoid  dislodging  dirt  from  cow's  hair. 
At  least  four  streams  of  foremilk  from  each  teat  to  be  discarded 
into  a  separate  vessel. 

V.  Cooling.     Cooled  within  fifteen  minutes  of  milking,  to  temperature 

below  45  degrees  F. 

Handling, — in  a  room  used  exclusively  for  handling  milk,  and  free 
from  dust,  dirt  and  odors  ;  and  the  milk  after  being  cooled,  always 
at  a  temperature  below  45  degrees. 

Protection  during  transportation.      Protected  from  dirt  by  tightly 
•  closed  receptacles,  temperature  always  below  45  degrees  F. ;  not 
delayed  in  transit,  reaching  market  within  twenty-six  hours  after 
milking. 

Through  the  efforts  of  the  Dairy  Division,  Bureau  of  Ani- 
mal Industry,  U.S.  Department  of  Agriculture,  the  score  card 
is  being  widely  used  by  municipalities.  On  June  30th,  1908, 
the  score-card  system  of  inspection  had  been  adopted  in  60 
cities  of  the  United  States,  located  in  25  states,  and  in  one 
Canadian  city.  A  score  card  for  use  in  California  should  be 
slightly  modified  to  meet  local  conditions.  On  account  of  the 
milder  climate,  cows  are  not  confined  in  the  stable  so  long  and 
ventilating  systems,  etc.,  are  of  less  importance.  The  score 
card  need  not  necessarily  be  recognized  in  legislation,  for  the 
publication  by  the  board  of  health  of  .the  scores  of  the  dairies 


INSPECTION. 


103 


furnishes  an  incentive  for  improvement.     An  example  of  legal 
recognition  of  the  score  card  is  as  follows  : 

"  STANDARD  BASKD  ON  SCORE 'CARD.  No  milk  shall  hereafter  be  sold 
or  offered  for  sale  or  exchange  in  the  city  of  New  Brunswick  which  shall 
be  produced  in  dairies  having  a  rating  below  60  per  cent,  as  based  on  the 
score  card  adopted  by  the  Board  of  Health,  City  of  New  Brunswick,  State 
of  New  Jersey." 

Improvement  in  Richmond,  \*a.  The  score  card  has  been 
found  a  useful  means  for  recording  the  improvements  in  the 
equipment  and  methods  of  milk  production.  The  results  ob- 
tained by  Levy  (12)  in  Richmond,  Virginia,  are  most  striking. 
The  inauguration  of  a  system  of  dairy  inspection  in  which  the 
score  card  was  used  gave  opportunity  for  recording  the  change 
in  dairy  conditions  from  month  to  month.  The  results  are 
given  in  tabular  form  below. 

TABLE  IV. 

THE  PERCENTAGE  OF   DAIRY  FARMS  IN  VARIOUS  CLASSES  DUR- 
ING   THE    FIRST   TWELVE    MONTHS   OF   DAIRY 
INSPECTION  IN  RICHMOND,  VA. 


May  /,  1907,  to  May  /,  1908. 


ClyASS. 


Scoring  below  30 

Scoring  between  30  and  40 

Scoring  between  40  and  50 

Scoring  between  50  and  60 

Scoring  between  60  and  70 

Scoring  between  70  and  80 

Scoring  between  80  and  90  .... 


Average  of  all  scores  for  month. 


PERCENTAGE  OF  ALL  DAIRIES  INSPECTED  FOR 
THE  MONTH  WHICH  FELL  IN  EACH  CLASS. 


1907 

1908 

I 

I 

1 

bj 

I 

"o 

p 

\ 

9 

1 

1 

"| 

13.8 

26.5 

3.9 

4.0 

30.8 

42.9 

21.0 

10.7 

26.2 

22.4 

38.2 

29.4 

40.0 

23.7 

14.8 

15.8 

2.8 

13.8 

8.2 

22.4 

33.3 

45.0 

35.6 

45.9 

36.8 

11.3 

13.6 

6.8 

5.7 

10.8 

13.2 

22.6 

12.5 

33.9 

29.5 

23.6 

35.2 

44.1 

39.8 

34.3 

4.6 

1.3 

3.5 

6.8 

8.2 

18.4 

31.0 

25.4 

34.2 

42.9 

1.6 

5.4 

19.7 

16.9 

19.2 

17.1 

41.5 

36.4 

47.5 

50.5 

51.4 

57.0 

58.4  60.5 

70.4  69.6 

71.5 

72.0 

The  results  are  shown  in  graphic  form  in  Fig.  14. 


104 


MUNICIPAL  SANITARY  CONTROL  OF  MILK. 


Fig.  14.     Diagram  shouting  improvement  in   dairv  scores 
mond,  \ra. 


Washington  milk  supply.  Webster  (17)  has  reported  the 
scores  of  the  dairies  supplying  Washington  as  shown  in  the 
following  table  : 

TABLE  V. 
SCORES  OF  DAIRIES  SUPPLYING  WASHINGTON. 


Scoring  from 

Virginia. 

Maryland. 

District  of  Columbia. 

.Number. 

%  of  all. 

Number. 

%  of  all. 

Number. 

%  of  all. 

0  to    10  ... 

' 

A  

10  to    20 

4 

76 

^f 

20  to    30  ..... 

7 

2.18 

76 

14.44 

2 

3.02 

30  to    40  ... 

44 

14.96 

173 

32.85 

7 

10.60 

40  to    50  ... 

83 

28.23 

164 

31.18 

13 

19.69 

50  to    60  

89 

30.20 

74 

14.01 

21 

31.81 

60  to    70  ..', 

53 

18.02 

22 

4.18 

13 

19.69 

70  to    80  

14 

4.42 

10 

1.90 

9 

13.63 

80  to    90  ... 

3 

1.02 

3 

.55 

1 

1.51 

90  to  100  ... 

1 

.34 

activities.     The  Dairy  Division  of  the  Bureau  of 
Animal  Industry  has  further  encouraged  education  as  a  factor 


INSPECTION.  105 

in  the  improvement  of  the  milk  supply.  In  co-operation  with 
the  Cleveland  (Ohio)  Chamber  of  Commerce,  a  city  milk  and 
cream  contest  was  held  (ll).  The  entries  in  all  classes  were 
judged  with  the  assistance  of  score  cards,  A  satisfactory 
number  of  entries  was  made,  and  the  interest  in  results  con- 
stituted a  potent  educational  factor. 

Important  features  in  dairy  practice  may  be  emphasized  by 
the  use  of  posters  printed  on  muslin,  like  that  in  Appendix  E. 

Inspection  of  cows.  The  examination  of  the  cows  should  in- 
clude a  manipulation  of  the  udder  in  each  case,  for  by  this 
means  only  can  udder  disease  be  detected.  In  suspicious 
cases,  a  little  milk  should  be  drawn  from  each  teat.  Among 
the  conditions  revealed  may  be  acute  mammitis,  various  skin 
eruptions,  external  abscesses  of  the  udder  or  teats,  etc.  Vary- 
ing degrees  of  induration  due  to  mammitis  are  not  uncommon. 
A  very  marked  hardening  of  one  or  more  quarters  may  be  due 
to  tuberculosis,  but  the  correctness  of  the  suspicion  is  best 
verified  by  a  bacteriological  "examination  of  the  discharge,  if 
any  is  obtainable.  Other  objectionable  conditions  are  more 
easily  recognized,  such  as  the  various  inflammatory  conditions 
which,  when  neglected,  give  rise  to  offensive  odors.  It  is  the 
general  practice  to  keep  such  minor  cases  in  the  regular  milk- 
ing herd,  and  to  neglect  rather  than  treat  the  conditions.  A 
much  more  satisfactory  arrangement  would  be  afforded  by 
arranging  a  hospital,  where  all  cows  with  disgusting  affections 
could  be  milked  and  treated. 

Inspection  of  dairy  apparatus.  Excellence  of  technic  is  of 
fundamental  importance  in  milk  production,  and  the  condition 
of  utensils,  is  an  excellent  index  of  the  standard  prevailing  in 
the  dairy.  The  sources  of  contamination,  with  reference  to 
utensils  and  methods  of  avoiding  them  are  discussed  in  Chap- 
ters I  and  IX.  There  are  certain  pieces  of  dairy  apparatus 
that  invite  neglect  in  cleaning  and  merit  particular  attention. 
Milk  pumps,  milking  machines,  bottling  machines,  rubber 
pipe,  faucets,  metal  pipes  with  elbows,  rusty  pails,  strainers 
(both  metal  and  cloth)  all  are  danger  points  with  reference 
to  the  contamination  of  milk. 

In  the  care  of  milk  utensils  is  to  be  found  the  one  great  uni- 


106  MUNICIPAL  SANITARY  CONTROL  OF  MILK. 

versal  fault  of  ordinary  dairymen  ;  namely,  that  the  heating  of 
utensils  after  washing  is  not  thoroughly  done. 

Inspection  of  water  supply.  The  source  of  the  water  supply 
with  reference  to  possible  contamination  by  the  germs  of 
typhoid  fever  is  of  great  importance.  There  are  many  ways 
in  which  contaminated  water  may  become  a  source  of  danger 
to  milk.  Deliberate  watering  of  milk,  accidental  watering 
through  leaks  in  apparatus,  or  rinsing  apparatus  in  cold  water, 
are  some  of  the  more  common  channels  of  contamination. 

If  the  supply  is  from  a  shallow  dug  well,  its  relation  to  the 
privy  or  area  where  chamber  slops  are  thrown  out  deserves 
careful  attention.  The  possibility  of  contamination  by  under- 
ground drainage  depends  upon  the  character  of  the  soil,  the 
slope  of  the  land  and  the  distance.  It  certainly  is  not  asking 
too  much  that  the  privy  be  at  least  100  feet  from  the  well  un- 
der any  condition.  The  protection  of  the  well  from  surface 
drainage  is  important.  Chickens  will  visit  the  privy  vault  if 
they  have  opportunity,  and  then  may  go  to  the  puddle  of  water 
around  the  well  for  a  drink. 

Driven  wells  offer  similar  dangers  of  contamination  from 
holes  in  casings,  but  in  general  furnish  a  more  reliable  source 
of  water.  Springs  and  streams  offer  obvious  possibilities  for 
contamination.  Bolton  (l,  2)  has  very  thoroughly  discussed 
the  subject  of  water  supply  for  dairies  and  the  bacteriological 
examination  of  the  same. 

Scope  of  inspection.  .Every  stage  in  the  progress  of  milk  from 
the  dairy  to  the  consumer  offers  conditions  necessitating  sani- 
tary supervision.  Attention  should  be  paid  to  milk  at  the 
farm,  during  transportation  to  shipping  point,  at  shipping 
point,  during  railroad  transportation,  at  the  railroad  station, 
at  the  city  dairy  depot,  on  city  wagons  and  in  the  retail  store. 
It  is  well  to  go  even  farther  and  instruct  the  consumer  about 
the  care  of  milk.  Methods  of  transportation  attract  particular 
attention  in  relation  to  speed  and  means  employed  for  refriger- 
ation. The  distributing  milk  depot  offers  opportunity  for 
re-infection  from  utensils  or  attendants. 

Tlie  score  card  for  city  milk  plants.  The  inspection  of  city 
milk  plants  is  likewise  facilitated  by  the  use  of  the  score  card. 


V.  S.  DEPARTMENT  OF  AGRICULTURE,  BrRKA.r  OF  ANIMAL  INDUSTRY, 
DAIRY  DIVISION. 

SANITARY  INSPECTION  OF  CITY  MILK  PLANTS. 

Owner  or  Manager..  Trade  name 

City Street  and  No State 

Number  of  wagons Gallons  sold  daily  \  rveam 

Peimit  or  license  No Date  of  inspection 190 


SCORE. 

REMARKS. 

Perfect. 

Allowed. 

MILK    ROOM. 

Location 

Construction  — 
Floor  3  | 
\Vallsand  ceiling  3  > 
Drainage...         4J 
Cleanliness 
Light  and  ventilation  
Equipment  — 
Arrangement  3  } 
Con  str  uct  io  n  — 
Sanitary  2  1 
Durability  2 
Condition  3 
Cleanliness                     5 

10 

10 

15 
10 

15 

20 
10 

10 



MILK. 

Handling                      .121 
Storage  ....                    .....  8  f 

SALES   ROOM. 

Location  ...           2  } 
Construction  ...             2  [ 
Equipment.....               2  ( 
Cleanliness                        4J 

WAGONS. 

General  appearance  2  j 
Protection  of  product  ..3  V 
Cleanliness                         5  J 

Total 

,       100 

Sanitary  conditions  are  .  . 
Suggestions  by  inspector 


Excellent. 


Good. 


.Fair Poor 


Signed .... 


Inspector. 


108  MUNICIPAL  SANITARY  CONTROL  OF  MILK. 

\  Reverse.'} 

SANITARY  INSPECTION  OF  CITY  MILK  PLANTS. 
DIRECTIONS  FOR  SCORING. 

MILK    ROOM. 

Location. — If  not  connected  by  door  with  any  other  building,  and  sur- 
roundings are  good,  10;  when  connected  with  other  rooms,  such  as 
kitchens,  stables,  etc.,  make  deductions  according  to  conditions. 
Construction. — If  good  cement  floor,  and  tight,  smooth  walls  and  ceil- 
ings, and  good  drainage,  allow  10;  deduct  for  cracked  or  decayed  floors, 
imperfect  wall  and  ceiling,  etc. 

Cleanliness. — If  perfectly  clean  throughout,  allow  15  ;  deduct  for  bad 
odors,  unclean  floor  and  walls,  cobwebs,  unnecessary  articles  stored  in 
room,  etc. 

Light  and  ventilation. — If  window  space  is  equivalent  to  \5%    or  more 
of  the  floor  space,  allow  5;  deduct  1  point  for  every  3$  less  than  the 
above  amount. 
Equipment: 

Arrangement. — Allow  3  points  for  good  arrangement;  if  some  of  the 
equipment  is  out  of  doors  or  so  placed  that  it  can  not  be  readily 
cleaned,  make  deductions  according  to  circumstances. 
Condition. — If  in   good   repair,  allow  4  points;    make  deductions  for 

rusty,  worn-out,  or  damaged  apparatus. 
Construction. — 

Sanitary:  If  seams  are  smooth,  and  all  parts  can  be  readily  cleaned, 

allow  2.     Deduct  for  poor  construction,  from  sanitary  standpoint. 

Durability:  If  made  strong  and  of  good  material,  allow  2.     Deduct 

for  light  construction  and  poor  material. 

Cleanliness. — If  perfectly  clean,  allow  8  points;  make  deductions  ac- 
cording to  amount  of  apparatus  improperly  cleaned. 

MI^K. 

Handling. — If  milk  is  properly  cooled  to  50°  F.  or  lower,  allow  12  points; 
or  if  pasteurized  at  a  temperature  of  149°  F.  or  above  and  promptly 
cooled  to  50°  or  lower,  allow  12  points.  Deduct  1  point  for  every 
2°  above  50°.  If  milk  is  pasteurized  imperfectly,  deduct  6  points.  If 
milk  is  improperly  bottled  or  otherwise  poorly  handled,  make  deduc- 
tions accordingly. 

Storage. — If  stored  at  a  temperature  of  45°  F.  or  below,  allow  8  points; 
deduct  1  point  for  every  2°  above  45°. 

SALES   ROOM. 

Location. — If  exterior  surroundings  are  good  and  building  is  not  con- 
nected with  any  other  under  undesirable  conditions,  allow  2;  for  fair 
conditions,  allow  1;  poor  conditions,  0. 


INSPECTION.  109 

Construction. — If  constructed  of  material  that  can  be  kept  clean  and  sani- 
tary allow  2;  for  fair  construction,  allow  1;  poor  construction,  0. 

Equipment.—  If  well  equipped  w4th  everything  necessary  for  the  trade, 
allow  2;  fair  equipment,  1;  poor  equipment,  0. 

Cleanliness. — If  perfectly  clean,  allow  4  points;  if  conditions  are  good,  2; 
fair,  1;  poor,  0. 

WAGONS. 

General  appearance. — If  painted  and  in  good  repair,  allow  2  points  ;  for 

fair  condition,  1;  poor,  0. 
Protection  of  Product. — If  product  is  iced,  allow  3  points;  well  protected 

but  not  iced,  1;  no  protection,  0. 
Cleanliness.— ?If  perfectly  clean,  allow  5;  good,  3;  fair,  2;  poor,  0. 

The  regulation  of  methods  of  pasteurizing  milk  is  one  of  the 
newer  problems  that  must  be  met  in  city  inspection  work. 
(See  Appendix  B.) 

Milk-borne  epidemics.  Present  methods  of  inspection  do  not 
prevent  the  occurrence  of  numerous  epidemics  of  typhoid  fever, 
diphtheria  and  scarlet  fever.  Much  can  be  done  in  the  way 
of  recognizing  such  outbreaks  early,  and  in  correcting  condi- 
tions at  the  source  of  trouble.  The  health  officer  should  inves- 
tigate the  milk  supply,  and  other  possible  sources  of  infection, 
of  all  reported  cases  of  these  diseases,  and  keep  a  record  of 
their  distribution  with  reference  to  the  various  dairymen. 
When  a  dairyman  shows  a  suspicious  number  of  cases,  due 
consideration  being  given  to  the  size  of  his  business  and  the 
general  prevalence  of  the  disease,  the  matter  should  be  in- 
vestigated. (See  Chap.  III.)  Pasteurization  (Chap.  VI)  seems 
to  be  the  only  way  of  preventing  outbreaks  of  milk-borne  dis- 
ease. 

The  Department  of  Health  of  the  City  of  New  York  has 
regulations  requiring  a  report  every  week  concerning  the  exist- 
ence of  infectious  diseases  among  those  handling  milk.  The 
dairymen  are  required  to  report  to  the  manager  of  the  shipping 
station  and  he  in  turn  notifies  the  health  department.  Kven 
if  these  regulations  were  uniformly  obeyed  they  would  not 
protect  against  bacilli  carriers.  (See  Appendix  D.) 

Temperature  standard.  New  York,  Boston,  and  other  cities 
require  that  milk  be  immediately  cooled  to  50°F.  or  below, 


110  MUNICIPAL  SANITARY  CONTROL  OF  MILK. 

and  that  it  shall  not  exceed  this  temperature  before  delivery. 
The  requirement  is  desirable,  and  does  not  necessitate  compli- 
cated methods  of  examination.  This  regulation  very  properly 
necessitates  the  use  of  ice  at  the  producing  farm,  and  the  use 
of  refrigerator  .cars  where  the  milk  is  transported  long  dis- 
tances. Its  strict  enforcement  tends  to  eliminate  the  sale  of 
milk  from  stores  where  adequate  refrigerating  facilities  are  not 
provided . 

In  a  large  area  of  the  country,  the  Southern  States  and 
California,  the  universal  enforcement  of  such  a  standard  is 
out  of  the  question  because  of  the  absence  of  natural  ice.  In 
large  dairies,  artificial  refrigeration  may  be  used,  but  the  smaller 
producers  could  not  afford  the  expense. 

Numerical  determinations  of  bacteria  in  milk.  Bacterial  counts 
may  be  made  to  yield  valuable  information  when  conditions 
that  will  permit  the  comparison  of  results  are  maintained.  The 
first  requisite  is  the  practice  of  uniformity  in  technic.  Under 
such  conditions,  the  examination  of  the  milk  from  time  to 
time  from  samples  of  the  same  age  will  reveal  significant  devi- 
ations from  the  usual.  Then  an  unusually  high  count  wrill 
indicate  the  effect  of  the  combination  in  some  proportion  of 
the  factors  of  uncleanliness,  age  and  poor  cooling. 

Numerical  determinations  of  bacteria  are  an  index  of  the 
care  exercised  in  the  handling  of  milk.  A  sufficient  number 
of  determinations  give  results  that  permit  the  classification  of 
dairies  in  a  general  sort  of  way.  Systematic  counting  of  bac- 
teria in  a  city  milk  supply  encourages  better  methods.  Rela- 
tively high  counts  Occurring  uniformly  are  unmistakable  evi- 
dence of  bad  management. 

Nice  distinctions  among  dairies  supplying  a  city  cannot  be 
made  on  the  .basis  of  a  variation  of  a  few  million  bacteria  per 
cc.  in  the  milk.  The  instrument  of  measurement  is  too  deli- 
cate in  such  cases  and  the  distinctions  revealed  too  fine. 

Effective  work  calls  for  faithful  attention  to  details  of  technic 
and  for  numerous  determinations.  Tests  made  at  rare  inter- 
vals from  samples  of  normally  bad  milk,  varying  considerably 
in  age,  represent  the  lowrest  degree  of  usefulness  of  the  work. 
The  sensational  publication  of  such  results  does  not  materially 


INSPECTION.  Ill 

protect  the  public  or  educate  the  dairymen.  Unless  bacterial 
counts  are  made  carefully  by  competent  persons  from  samples 
properly  collected  and  cared  for,  they  had  best  not  be  made  at 
all.  This  is  equally  true  in  cases  where  the  inspecting  staff 
is  too  small  or  too  inefficient  to  accomplish  the  work  thor- 
oughly. 

In  cities  like  Boston  (10),  Rochester  (7)  and  Washington 
(15),  bacterial  counts  in  connection  with  inspection  work  have 
been  made  on  a  scale  that  has  been  regarded  as  productive  of 
good  results.  The  average  bacterial  count  of  the  milk  of 
Rochester  declined  in  three  years  to  one-fourth  of  the  numbers 
prevailing  before  such  work  was  undertaken  (6). 

The  results  of  two  years'  work  with  a  bacterial  standard  in 
Boston  have  been  summarized  as  follows  by  Jordan  (10): 

TABLE   VI. 
NUMBER  OF  BACTERIA  IN  THE  BOSTON  MILK  SUPPLY. 

1905.         1906. 


Samples  showing  under  500,000  bacteria  per  cc 87.60%  89.98% 

Samples  showing  above  500,000  bacteria  per  cc 12.40%  10.02% 

Samples  showing  under    50,000  bacteria  per  cc 59.80%  62.33% 

Samples  showing  under  100,000  bacteria  per  cc 74.90%  72.67% 


As  is  usually  the  case,  the  determination  of  standards  has 
been  a  matter  of  difficulty.  They  have  been  set  on  the  basis 
of  the  justifiable  assumption  that  germ  free  milk  is  the  ideal 
milk.  Then,  after  a  survey  of  the  conditions  as  regards  num- 
bers in  the  ordinary  supply,  a  standard  has  been  set  low 
enough  to  interfere  only  with  the  worst  producers.  Boston  set 
a  limit  of  500,000  per  cc.  for  ordinary  city  supply,  and  has 
been  pretty  generally  followed.  Various  finer  grades  of  milk 
elsewhere  have  had  higher  standards,  for  instance,  inspected 
milk,  100,000  per  cc.  Certified  milk  almost  uniformly  has  a 
standard  of  10,000  per  cc.  A  bacterial  standard  need  not  be 
the  subject  of  legislation,  and  the  work  may  be  merely  carried 
on  as  a  guide  to  inspection  work. 


112  MUNICIPAL  SANITARY  CONTROL  OF  MILK. 

Bacterial  counts  take  so  long  to  carry  out  that  they  do  not 
afford  protection  against  the  use  of  any  given  lot  of  highly 
polluted  milk.  An  exception  to  this  is  afforded  when  Slack's 
method  for  the  direct  microscopic  estimate  of  numbers  is  used. 
Ordinary  counts  do,  however,  discourage  the  habitual  occur- 
rence of  such  conditions.  The  method  of  making  numerical 
determinations  is  described  in  Chap.  VIII,  and  other  labora- 
tory methods  are  discussed  in  Chap.  VII. 

Education  of  the  public.  The  general  public  must  be  in- 
formed concerning  the  significance  of  clean  milk.  The  market 
for  cheap,  dirty  milk  must  be  destroyed  as  far  as  possible  by 
the  education  of  the  public  concerning  its  significance.  Clean 
milk  costs  more,  but  people  will  not  pay  the  increased  price 
until  they  see  the  advantage.  In  matters  concerning  legisla- 
tion and  prosecution,  the  support  of  the  public  is  desirable,  if 
not  indispensable. 

The  publication  of  the  results  of  scoring  dairies,  showing 
their  relative  standing  is  a  useful  educational  factor.  This 
must  be  done  circumspectly  to  avoid  damage  suits  instituted  by 
those  dairymen  who  do  not  make  a  favorable  showing.  It 
seems  safe  to  convey  these  facts  in  an  official  report,  for  in- 
stance, by  the  inspector  or  health  officer  to  the  board  of  health. 
This  report  may  be  given  wide  publicity  in  the  press  as  a  part 
of  the  proceedings  of  the  board.  Before  going  farther  than 
this  it  would  be  well  to  determine  the  possible  consequences. 

Public  education  should  include  matters  concerning  the  care 
of  milk  in  the  home,  such  as  cleanliness  of  utensils,  refriger- 
ation, home  pasteurization  and  the  keeping  qualities  of  pas- 
teurized milk. 

The  agents  for  accomplishing  educational  work  may  include 
leaflets  published  by  the  board  of  health,  the  press,  lectures 
before  civic  organizations,  women's  clubs,  etc. 


REFERENCES. 

1.  BOI/TON.  Sanitary  water  supplies  for  dairy  farms.  Bui.  No.  41, 
Hyg.  Lad.,  ('.  S.  Pud.  Health  and  Mar.  Hosp.  Sen'.,  Washington,  D. 
C.,  1908,  p.  527. 


RKFKRKNCES.  113 

2.  BOSTON.     Methods  and  results'  of  the  examination  of  water  sup- 
plies of  dairies  supplying  the  District  of  Columbia.     Bui.  No.  41,  Hyg. 
/.ah.,    I'.  S.  Pub.   Health   and  Mar.  Hasp.  Sen'.,  Washington,  D.  C., 
1908,  p.  543. 

3.  CONFERENCE  APPOINTED  BY  THE  COMMISSIONERS  OF  THE  DISTRICT 

OF  COLUMBIA.     Sanitary  milk  production,     dr.  No.  114,  Bur.  Anhn. 
I  mi.,  ('.  S.  Hcpt.  Agr.,  Washington,  D.  C.,1907. 

4.  DARLINGTON.     The  methods  of  dealing  with  the  milk  supply  of 
New  York  City.    Jour.  Aiucr.  Med.  Assoc.,  Vol.  XUX,  1907,  p.  1079. 

5.  FRASER.     City  milk  supply.     Bui.  No.  92,  Univ.  of  III.  Agr.  Exp. 
Sta.,  Urbana,  111.,  1903. 

6.  GOLER.     The  influence  of  the   municipal   milk   supply  upon  the 
deaths  of  young  children.     N.   Y.  State  Jour,  of  Med.,  Vol.  Ill,  1903, 
p.  493. 

7.  GOLER.     Does  the  bacterial  content  of  city  milk  influence  the  in- 
fantile death  rate?     Archiv.  Fed.,  September,  1906. 

8.  HEINEMANN.     Sanitary  milk.     Arch.  Fed.,  June,  1908. 

9.  JAFFA  and  WARD.     Investigations  of  the  San  Francisco  milk  sup- 
ply.    Nineteenth  Biennial  Report  of  the  State  Board  of  Health  of  Cali- 
fornia, p.  122. 

10.  JORDAN.     Boston's  campaign  for  clean  milk.    Jour.  Amer.  Med. 
Assoc.,  Vol.  XUX,  1907,  p.  1082. 

11.  LANE  and  WELD.     A  city  milk  and  cream  contest  as  a  practical 
method  of  improving  the  milk  supply.     Cir.  No.  117,  Bur.  Anhn.  Ind., 
r.  5.  Dept.  Agr.,  Washington,  D.  C.,  1907. 

12.  L/EVY.     Monthly  Bulletin  of  the  Health  Department.    Richmond, 
Va.,  Vol.  II,  1908,  No.  4. 

13.  MAYOR'S  MILK  COMMISSION.    Report  on  the  milk  supply  of  New 
York  City,  with  recommendations.     Arch.  Ped.,  February,  1908. 

14.  RAYNOR.     What  rigid  inspection  of  milk  is  doing  for  New  York 
City.     N.  Y.  State  Jour,  of  Med.,  Vol.  VIII,  1908,  p.  252. 

15.  ROSENAU.     The   number  of  bacteria  in   milk,  and  the  value  of 
bacterial  counts.     Bui.  No.  41,  Hyg.  Lab.,  U.  S.  Pub.  Health  and  Mar. 
Hosp.  Serv.,  Washington,  D.  C.,  1908,  p.  421. 

16.  TRUEMAN.     Milk  supply  of  Chicago  and  twenty-six  other  cities. 
Bui.  No.  120,  Univ.  of  III.  Agr.  Exp.  Sta.,  Urbana,  111.,  1907. 

17.  WEBSTER.       Sanitary  inspection  and  its  bearing  on  clean  milky 
Bui.  No.  41,  Hyg.  Lab.,    U.  S.  Pub.  Health  and  Mar.  Hosp.  Sen£, 
Washington,  D.  C.,  1908,  p.  511. 

18.  WOODWARD.     The   municipal  regulation  of  the  milk  supply  of/ 
the  District  of  Columbia.     Bui.  No.  41,  Hyg.  Lab.,  U.  S.  Pub.  Health 
and  Mar.  Hosp.  Serv.,  Washington,  D.  C.,  1908,  p.  679. 


CHAPTER  VI. 


PASTEURIZATION  OF  MILK, 


General  definition*  Pasteurization  is  a  generic  term  refer- 
ring to  various  processes  of  heating  milk,  followed  by  cooling. 
The  temperatures  involved  vary  from  140°F.  (60°C.) to  185°F. 
(85°C.)  and  the  length  of  time  of  exposure  to  these  tempera- 
tures varies  from  a  few  seconds  to  thirty  minutes.  A  consider- 
able number  of  pasteurizing  machines  designed  to  accomplish 
the  heating  of  the  milk  in  various  ways  are  in  use,  and  in 
actual  practice  do  their  work  with  varying  degrees  of  uni- 
formity. The  temperature  to  which  the  milk  is  finally  cooled, 
an  important  factor  in  the  efficiency  and  value  of  the  process, 
likewise  varies.  Another  element  leading  to  diversity  of 
results  is  the  bacteriological  quality  of  the  milk  treated  by  the 
processes.  Notwithstanding  the  widely  differing  processes 
designated  by  "  pasteurization,"  the  term  unfortunately  is  con- 
stantly used  without  qualification  to  indicate  the  precise  process 
designated. 

Sterilization,  a  term  frequently  used  in  the  discussion  of  the 
subject  of  heated  milk,  properly  refers  to  a  process  by  which 
all  bacteria  and  their  spores  are  killed  by  heat.  This  in  con- 
nection with  the  preservation  of  milk  involves  an  exposure  to 
heat  above  the  boiling  point.  It  is  employed  in  the  preser- 
vation of  canned  milk  and  never  in  connection  with  ordinary 
market  milk. 

Incentives  for  pasteurization.  The  destruction  of  pathogenic 
bacteria  has  been  the  chief  incentive  to  the  development  of 
pasteurizing  processes.  The  effect  of  heating  in  enhancing 
the  keeping  quality  of  milk  is  a  valuable  result  which  also  has 
stimulated  interest  in  the  process.  Methods  for  preserving 
milk  are  not  necessarily  the  same  as  for  killing  pathogenic  bac- 
teria, although  the  converse  is  true. 


ALTERATION  OF  MILK  BY  HEAT.  115 

Conditions  required  for  killing  bacteria.  Temperature  and 
time  of  exposure  are  important  factors  with  reference  to  meth- 
ods of  killing  bacteria  by  heat.  A  high  temperature  foi^a 
short  time  is  equally  as  efficient  as  a  lower  temperature  for  a 
longer  time. 

Bacterium  tuberculosis.  This  is  the  most  common  of  the 
pathogenic  organisms  found  in  milk,  and  at  the  same  time  the 
one  of  them  most  resistant  to  heat.  Therefore  it  has  been  used 
as  a  basis  for  determining  methods  of  pasteurizing,  with  proper 
regard  to  other  considerations  not  concerning  bacteria.  The 
fact  that  140°F.  (60°C.)  for  twenty  minutes  is  fatal  to  Bacterium 
tuberculosis  is  abundantly  confirmed  (13,  16,  20).  This  is 
•equally  true  of  the  other  pathogenic  bacteria  like  B.  diphtheria' 
and  B.  typhosus,  occasionally  disseminated  in  milk  (13). 

To  kill  the  tubercle  bacterium,  when  the  time  of  exposure 
of  heat  is  shortened  to  one  minute  or  less,  the  temperature 
must  be  160°F.  (71°C.)  or  more  (6,  18).  B.  diphtheria  (13) 
and  B.  typhosus  (9)  are  destroyed  in  like  manner. 

.Alteration  of  milk  by  heat.  The  bacteriological  requirements 
are  by  no  means  the  only  factors  in  the  problem,  for  the  heating 
of  milk  presents  a  formidable  array  of  obstacles  that  must  be 
avoided  in  formulating  pasteurization  processes.  These  in- 
volve all  sorts  of  considerations,  from  those  concerning  the 
chemical  constitution  of  the  heated  milk  with  respect  to  nutri- 
tion, to  the  practical  requirements  of  the  milk  trade. 

Cooked  taste.  This  is  left  permanently  in  milk  by  exposure 
to  about  158°F.  (70°C.)  for  fifteen  minutes.  Exposure  to 
170°F.  (76.6°C.)  in  a  closed  vessel,  followed  by  immediate 
cooling,  is  the  highest  temperature  that  may  be  used  without 
leaving  the  cooked  taste.  Ten  minutes  at  160°F.  (7l°C.)  is 
safe. 

Alterations  of  milk  constituents.  The  chemical  constitution 
of  milk  is  not  appreciably  altered  by  exposure  to  140°F.  (60°C.) 
for  a  short  time.  At  about  140°F.,  milk  heated  with  exposure 
to  air  forms  a  thin  pellicle  on  the  surface,  consisting  of  casein 
and  albuminoid  matter.  This  is  probably  due  to  the  drying 
of  the  upper  layer  of  the  milk  and  does  not  occur  in  closed 
vessels.  Higher  temperatures,  especially  near  the  boiling 


116  PASTEURIZATION  OF  MILK. 

point,  bring  about  profound  changes.  The  .significance  of 
these,  in  connection  with  the  digestibility  of  the  altered  con- 
stituents, has  been  widely  discussed.  Important  manifestations 
of  the  effect  of  heat  on  milk  concern  temperatures  higher  than 
those  necessary  for  pasteurization. 

Creaming  quality .  Exposure  to  heat  above  certain  limits  so 
alters  the  physical  constitution  of  milk  that  the  cream  does  not 
rise  naturally  but  remains  more  completely  emulsified.  The 
public  judges  milk  largely  by  the  amount  of  cream  that  rises, 
especially  in  the  case  of  bottled  milk  where  the  location  of  the 
"cream  line"  is  so  easily  detected.  The  same  causes  that 
operate  in  this  regard  in  milk  affect  market  cream.  The 
"  body  "  is  lessened,  the  cream  looks  of  a  poorer  quality  than 
it  really  is,  its  whipping  quality  is  affected,  and  consequently 
its  salability  is  impaired.  These  are  weighty  considerations 
and  the  application  of  heat  must  conform  to  them.  Exposure 
to  160°F.  (71°C.)  for  one  minute,  or  long  exposures  at  140°F. 
(60°C.)  are  both  safe  (2). 

Vital  qualities  of  milk.  Milk  has  certain  vital  qualities, 
whose  sensitiveness  to  heat  deserves  especial  consideration  with 
respect  to  the  use  of  heated  milk  as  infant  food.  Among  these 
are  the  proteolytic,  oxidizing,  and  fat  splitting  ferments. 
Here,  too,  may  be  mentioned  the  alexins,  according  to  Von 
Behring,  and  the  agents  causing  the  so-called  "  germicidal  " 
phenomenon,  probably  agglutinins.  An  exposure  to  not  more 
than  140°F.  (60°C.)  for  forty  minutes  avoids  the  impairment  of 
all  these  qualities  of  milk  (3,  5). 

Spore- bear  ing  bacteria.  Spores  of  bacteria  in  milk  are  not 
killed  by  one  exposure  to  heat  unless  it  is  above  212CF.  Any 
of  the  processes  of  pasteurization  will  fail  to  kill  bacterial 
spores,  that  ordinarily  constitute  less  than  \%  of  the  bac- 
teria present.  The  hygienic  significance  of  spore-bearing 
bacteria  in  such  small  numbers  in  fresh  pasteurized  milk  is  of 
no  consequence,  and  the  fact  of  their  survival  has  been  of 
necessity  ignored  in  formulating  methods  of  pasteurization. 
Their  significance  in  old  pasteurized  milk  has  been  the  subject 
of  considerable  discussion.  The  varying  percentage  of  spores 
in  different  lots  of  milk  results  in  the  variation  of  the  bacteri- 


LOW  -TEMPER  ATURE  PASTEURIZATION.  117 

cidal   efficiency  of  a  pasteurizing  machine  at  different  times, 
even  if  run  under  constant  conditions. 

Bactericidal  efficiency.  Russell  (15)  has  shown  that  an 
exposure  to  140°F.  (60°C.)  for  twenty  minutes  results  in  the 
destruction  of  as  great  a  number  of  bacteria  as  exposure  to 
higher  temperatures  for  the  same  time.  The  bacteria  remain- 
ing alive  after  exposure  to  160°F.  were  in  spore  form,  and  were 
uninjured  by  the  higher  ranges  of  temperature.  Milk  which 
would  ordinarily  sour  in  two  days  would  keep  fresh  for  six 
days  when  pasteurized  at  140°F.  for  fifteen  to  thirty  minutes 
(2).  Over  99%  of  the  bacteria  were  killed. 

Low-temperature  pasteurization*  The  various  limitations  to 
the  application  of  heat  for  the  purpose  of  killing  bacteria  per- 
mit the  use  of  140°F.  (60°C.)  for  twenty  minutes.  All  the 
physical,  chemical  and  bacteriological  considerations  involved 
favor  the  selection  of  this  combination  of  time  and  temper- 
ature, for  it  presents  the  widest  margin  of  safety  from  violation 
of  the  limiting  conditions. 

The  earliest  machines  for  accomplishing  low  temperature 
pasteurization  embodied  the  idea  of  heating  a  definite  quantity 
of  milk,  -with  proper  agitation,  to  the  required  temperature, 
after  which  the  milk  was  rapidly  chilled.  The  principle  of  a 
reservoir,  alternately  filled  and  emptied,  is  common  to  many. 
In  some,  heating  and  chilling  the  milk  are  accomplished  in  the 
same  chamber.  The  process  of  intermittent  pasteurization  in 
the  reservoir  type  of  machine  necessitates  considerable  expense 
for  labor  and  is  slow.  These  considerations  have  largely  pre- 
vented the  general  employment  of  the  type  of  machine  in  ques- 
tion. There  are  no  insurmountable  difficulties  in  the  way  of 
the  development  of  machines  for  accomplishing  low  temper- 
ature pasteurization  at  a  rate  of  speed  and  low  cost  appropriate 
to  the  demands  of  milk  distributers.  There  are  now  on  the 
market  machines  designed  to  hold  the  milk  at  a  given  temper- 
ature for  twenty  or  thirty  minutes,  and  at  the  same  time 
permit  continuous  operation.  The  milk  is  first  heated  and 
then  passed  through  a  ' '  holding  device ' '  by  which  the  desired 
temperature  is  maintained  for  the  proper  time. 

The  pasteurizing  process  may  be  carried  out  in  the  house- 


118  PASTEURIZATION  OF  MILK. 

hold  with  kitchen  utensils,  it  being  necessar\^  to  purchase  only 
a  thermometer.  The  bottles  of  milk  for  individual  feeding  of 
the  infant  are  placed  in  a  covered  vessel  of  water  provided  with 
some  simple  device,  like  a  perforated  pie  tin,  to  keep  the  milk 
bottles  from  touching  the  bottom.  The  vessel  and  contents 
are  heated  on  the  stove  until  the  water  reaches  155°F.  The 
whole  is  removed  and  allowed  to  stand  for  half  an  hour,  after 
which  the  bottles  of  milk  are  rapidly  chilled. 

High-temperature  pasteurization.  The  demand  for  speed 
and  economy  has  been  a  factor  in  the  development  of  pasteur- 
ization at  high  temperatures  for  a  short  time.  The  heating  is 
accomplished  in  various  styles  of  continuous-flow  machines, 
iii  which  the  milk  passes  over  heated  surfaces  in  a  thin  layer. 
The  range  of  temperature  extends  from  176°F.  (80°C.)  to  185°F. 
(85°C.),  and  the  time  of  exposure  varies  from  a  few  seconds 
upwards.  The  momentary  exposure  to  176°F.  (80°C.)  is  con- 
siderably above  that  necessary  to  satisfy  the  requirement  for 
killing  tubercle  bacilli.  The  higher  limit  has  been  found 
necessary  to  compensate  for  defects  in  the  thoroughness  with 
which  the  continuous-flow  machines  do  their  work.  As  a  class 
the  machines  are  defective,  in  that  all  the  milk  passing  through 
may  not  be  heated  to  the  desired  temperature.  This  is  attribu- 
table to  a  fundamental  characteristic  of  the  behavior  of  fluids. 
The  parts  of  the  stream  not  in  actual  contact  with  the  heated 
surfaces  will  flow  more  rapidly  than  those  portions  influenced 
by  friction.  The  employment  of  a  temperature  as  high  as 
176°F.  (80°C.)  violates  conditions  required  for  market  milk 
in  the  United  States,  but  the  process  is  unobjectionable  in  milk 
used  for  butter-making  and  is  extensively  employed  in  Den- 
mark for  this  purpose. 

Commercial  pasteurization.  A  modification  of  the  foregoing 
method,  by  the  use  of  the  same  types  of  continuous-flow 
machines,  is  quite  generally  used  -for  the  purely  commercial 
purpose  of  preventing  the  souring  of  milk.  It  hides,  and  par- 
tially undoes,  the  results  of  filthy  methods  of  production  and 
poor  care  in  shipment. 

The  temperatures  vary  from  140°  to  165°F.  (60°  to  74°C.), 
more  often  the  lower  temperature,  followed  by  rapid  cooling. 


HIGH-TKMPERATURK   PASTEURIZATION.  119 

The  time  occupied  by  the  milk  in  passing  through  the  machine 
is  varied  at  the  will  of  the  operator,  from  a  fraction  of  a  min- 
ute to  two  minutes.  The  fact  that  this  method  of  treating  milk 
has  come  into  practice  without  consideration  of  its  effect  upon 
the  pathogenic  organisms  becomes  evident  when  attention  is 
paid  to  the  literature  on  the  thermal  death  point  of  the  tubercle 
bacterium  in  milk  at  temperatures  between  140°  and  160°F. 
At  140°F  (60°C.),  the  shortest  length  of  time  that  has  been 
found  permissible  is  fifteen  minutes  (20).  Heating  milk  to  this 
temperature  or  even  several  degrees  above  for  a  minute  or  less 
is  a  long  way  from  the  conditions  insuring  the  death  of  the 
tubercle  organism.  Hess  (Ref.  9,  Chap.  IV)  has  noted  the 
deficiencies  of  commercially  pasteurized  milk  as  regards  de- 
struction of  tubercle  bacilli.  It  is  only  when  the  temperature 
of  the  milk  during  the  heating  for  brief  periods  approaches 
160°F.  (71°C.)  that  evidence  is  found  to  justify  the  belief  that 
pathogenic  organisms  are  killed. 

There  seems,  then,  to  be  justification  for  placing  confidence 
in  a  pasteurization  process,  as  a  means  for  destroying  patho- 
genic bacteria,  in  which  all  the  milk  is  actually  exposed  for 
half  a  minute,  or  even  momentarily,  to  a  temperature,  of  160°F. 
(71.1°C).  The  statement  need  not  necessarily  imply  an 
adherence  to  that  system  of  pasteurization  for  rendering  milk 
safe  as  against  a  system  employing  lower  temperatures  for 
longer  periods.  Commercial  high-temperature  pasteurization 
has  narrow  limits  of  safety  bounded,  on  the  one  hand,  by  alter- 
ations in  the  physical  characteristics  of  the  milk,  and  on  the 
other  hand,  by  the  danger  of  not  killing  pathogenic  bacteria. 
The  temperature  zone  in  question  comprises  160°  to  165°F., 
and  therefore  the  possibilities  of  negligence  in  running  the 
apparatus,  or  intentional  lowering  of  the  temperature  for  com- 
mercial reasons,  are  obvious.  There  is  always  the  possibility 
that  the  machine  in  use  may  not  heat  all  portions  of  the  milk 
uniformly  to  the  temperature  desired. 

Efficiency.  Efficiency  tests  of  pasteurization  must  be  inter- 
preted with  care.  The  bacteria  remaining  should  not  be  com- 
pared, with  respect  to  either  numbers  or  character,  with 
those  in  uuheated  milk.  The  character  of  the  organisms  in 


120  PASTEURIZATION  OF  MILK. 

heated  milk,  and  the  medium  in  which  they  are  present,  en- 
tirely preclude  comparisons  with  ordinary  milk  showing  a 
similar  count. 

Prescott  (10)  found  in  a  series  of  32  observations,  from 
samples  containing  mostly  less  than  a  million,  that  a  machine 
at  an  average  temperature  approximately  164°F.  attained  an 
average  percentage  efficiency  of  97.1%  .  The  bacteria  remain- 
ing in  the  milk  averaged  14,000  per  cc.  and  the  average 
temperature  of  the  pasteurized  milk  was  40°C.  Very  bad 
milk,  three  to  nine  million,  showed  the  high  efficiency  of 
99.1%,  with  an  average  of  55, 090  per  cc.  left  alive.  In  regu- 
lar practice  the  conditions  for  highest  efficiency  were  not 
always  maintained.  Russell  (15)  has  summarized  the  results 
of  a  number  of  such  tests  made  by  himself  and  others. 

Continuous-flow  machines  popular.  The  commercial  interests 
have  refused  to  adopt  generally  the  discontinuous  or  tank  type 
of  pasteurizing  machine  for  market  milk,  on  account  of 
expense  and  time  consumed,  although  it  is  used  for  cream. 
The  rapid,  cheaply  operated,  continuous  flow  machine,  run- 
ning at  140°  to  165°F.,  is  a  factor  in  the  market  milk  business 
to-day.  Lederle  (8)  estimates  the  expense  of  treating  milk  by 
this  process  to  be  from  one-tenth  to  one-quarter  of  one  cent 
per  quart.  However  much  bacteriologists  may  prefer  the  use 
of  140°F.  for  twenty  minutes,  the  other  practice  is  deeply 
rooted.  It  has  been  estimated  that  one-quarter  of  the  milk 
sold  in  New  York  is  pasteurized  and  about  one-third  of  that  in 
Boston  (12). 

Under  the  circumstances,  it  seems  that  a  fruitful  field  for 
persuasive  educational  effort  is  furnished  by  those  instances 
where  the  machine  is  so  run  that  the  milk  is  exposed  too  short 
a  time  at  a  temperature  below  160°F.  It  is  entirely  possible 
to  expose  milk  to  160°F.  for  a  minute  or  even  two,  without 
injuring  the  cream  line  or  flavor,  although  it  probably  does 
impair  certain  vital  characteristics.  Effort  should  be  made  to 
have  the  machines  run  at  160°F.  with  the  flow  of  milk  slow 
enough  to  permit  exposure  to  the  heat  for  at  least  one  minute. 
Better  yet,  the  employment  of  machines  heating  to  140°F.  for 
twenty  or  thirty  minutes  should  be  encouraged. 


PASTEURIZATION  IN  CHICAGO.  121 

Care  subsequent  to  heating*  The  milk  must  be  rapidly  and 
thoroughly  chilled  after  heating.  The  process  of  pasteuriza- 
tion should  include  cooling  to  at  least  50°F.,  and  any  regula- 
tions denning  the  process  should  make  reference  to  the  cooling. 
Unless  cooled,  the  few  bacteria  that  have  survived  the  heating 
will  multiply  in  the  warm  milk  at  an  enormous  rate.  Any 
opportunities  offered  for  contamination  subsequent  to  heating 
will  speedily  undo  the  beneficial  work  done  by  the  heat.  The 
method  of  handling  pasteurized  milk  for  infant  feeding  illus- 
trates an  ideal  way  of  avoiding  subsequent  contamination. 
The  milk  is  pasteurized  in  the  containers  from  which  the 
baby  is  fed. 

In  connection  with  this  subject,  interest  attaches  to  some 
recent  amendments  to  the  sanitary  code  of  the  Board  of  Health 
of  New  York,  as  follows : 

"1.  Pasteurization  of  milk  must  he  carried  out  under  a  permit  therefor 
issued  by  the  Board  of  Health,  in  addition  to  the  usual  permit  for  milk 
required  by  Section  56  of  the  Sanitary  Code. 

"2.  The  milk  after  pasteurization  must  be  at  once  cooled  and  placed 
in  sterilized  containers,  and  the  containers  sealed. 

"3.  All  pasteurized  milk  must  be  delivered  to  the  consumer  in  sealed 
containers  which  are  plainly  labeled  'pasteurized.'  The  labels  must  also 
bear  the  dat£  and  hour  when  the  pasteurization  of  the  milk  was  comple- 
ted, the  degree  of  the  heat  employed,  the  length  of  time  exposed  to  the 
heat,  and  the  number  of  the  pasteurization  permit  issued  by  the  Board 
of  Health. 

4 '  4.  Pasteurized  milk  must  be  delivered  to  the  consumer  within  twenty- 
four  hours  of  the  pasteurization. 

"5.     No  milk  shall  be  pasteurized  a  second  time." 

Pasteurization  in  Chicago,  Recent  legislation  in  Chicago 
requires  not  only  the  pasteurization  of  all  milk  obtained  from 
non-tested  cows  but  also  requires  that  all  butter,  cheese, 
buttermilk,  cream  and  ice  cream  shall  be  derived  from  pasteur- 
ized milk  unless  the  cows  are  free  from  tuberculosis.  A  num- 
ber of  new  administrative  difficulties  are  involved,  such  as 
inspection  of  pasteurization,  and  results  of  the  experience  with 
the  Chicago  ordinance  will  be  awaited  with  interest.  See 
Appendix  B. 


122  PASTEURIZATION  OF  MILK. 

Pasteurized  milk  in  infant  feeding.  The  use  of  heated  milk 
for  infant  feeding  is  widely  prevalent.  There  is  abundant 
medical  testimony  to  the  effect  that  properly  heated  milk  is 
harmless,  and  that  the  general  adoption  of  its  use  is  an  impor- 
tant factor  in  saving  life  ( 12) .  On  the  other  hand,  experienced ' 
specialists  in  pediatrics  vehemently  object  to  the  long-continued 
use  of  heated  milk  for  infant  feeding  and  point  with  truth  to 
cases  that  are  unable  to  tolerate  heated  milk. 

The  literature  of  the  subject  is  voluminous,  but  the  discus- 
sion in  general  has  not  been  concerned  with  clear-cut  issues. 
The  temperatures  to  which  milk  has  been  exposed  in  the  past, 
and  even  now,  are  higher  than  necessary.  All  sorts  of  tem- 
peratures have  been  used  and  insufficient  distinction  has  been 
drawn  between  sterilized  and  pasteurized  milk.  Reference  has 
been  made  to  the  possible  effect  of  toxins  of  bacterial  origin 
remaining  active  in  heated  milk,  but  really  very  little  is  known 
concerning  them.  It  has  been  asserted  that  the  few  spore- 
bearing  bacteria  surviving  the  heating  would  subsequently 
multiply  very  rapidly  with  harmful  effect.  It  has  been  shown 
however  that,  with  proper  refrigeration,  multiplication  goes  on 
slowly  (ll).  The  issues  to  be  determined  have  been  clouded 
by  the  interjection  of  ideas  regarding  the  effect  that  the  gen- 
eral practice  of  pasteurizing  would  have  on  the  care  exercised 
by  producers.  The  writer  is  not  yet  convinced  that  there  is  a 
strong  case  against  the  use  of  milk  heated  to  140°F.  for  twenty 
minutes.  Now  that  this  desirable  kind  of  pasteurization  is  in 
use,  it  would  be  well  to  take  up  on  a  large  scale  the  study  of 
the  effect  of  this  milk  upon  infant  morbidity  and  mortality,  as 
compared  with  unheated  milk.  The  whole  controversy  con- 
cerns only  the  effect  of  heated  milk  on  children  of  less  than 
three  years  of  age.  There  are  special  agencies  for  the  supply 
of  milk  for  infant  feeding,  and  more  will  be  provided  in  the 
future.  Under  these  conditions,  one  may  very  well  question 
the  advisability  of  viewing  the  whole  problem  of  municipal 
milk  inspection  from  the  standpoint  of  its  use  for  the  few 
infants  who  are  unable  to  tolerate  heated  milk.  Rosenau  (12) 
discusses  the  matter  fully. 


PASTEURIZATION  OK   MUNICIPAL  MILK   SUPPLIES.  123 

Pasteurization  of  municipal  milk  supplies.  The  subject  of 
the  pasteurization  of  milk  assumes  great  importance  in  con- 
nection with  the  transmission  of  epidemic  diseases  of  man. 
There  has  been  collected  a  formidable  list  of  instances  in  which 
milk  has  transmitted  .scarlet  fever,  diphtheria  and  typhoid  fever. 
The  work  in  Washington  shows  that  10%  of  the  typhoid  fever 
cases  are  plainly  attributable  to  milk.  In  that  city,  of  the 
dairymen  delivering  over  100,000  gallons  of  milk  during  the 
summer  months,  the  one  having  the  lowest  typhoid  fever  rate 
among  his  customers  has  a  thoroughly  up-to-date  system  of 
sterilizing  bottles  and  of  pasteurizing  milk  by  a  holding-device 
type  of  machine. 

The  system  of  dairy  inspection  of  the  District  of  Columbia 
is  not  preventing  milk-borne  typhoid  fever.  All  that  can  be 
done  is  to  detect  outbreaks  as  early  as  possible,  correct  the 
conditions  at  the  dairy,  and  count  the  cases  of  typhoid  fever 
as  they  continue  to  appear.  This  is  not  said  in  disparagement 
of  the  Health  Department  of  the  District  government,  for  it  is 
under  able,  conscientious  management. 

The  facts  brought  to  light  in  Washington  regarding  typhoid 
fever  alone  indicate  the  necessity  for  pasteurization,  and  if 
subsequent  work  elsewhere  brings  to  light  similar  conditions 
as  regards  this  and  other  milk-borne  diseases,  the  evidence  for 
the  necessity  of  pasteurization  will  be  overwhelming.  Cer- 
tain it  is,  that  pasteurization  offers  the  only  effective  measure 
that  may  be  immediately  put  in  force  against  the  danger  from 
bovine  tuberculosis.  That  disease  is  so  widely  prevalent  that 
the  rigicl  application  of  measures  against  the  sale  of  milk  from 
tubercular  cows  without  the  alternative  of  pasteurization  would 
cause  a  milk  famine. 

There  have  been  opinions  expressed  to  the  effect  that  pas- 
teurization would  discourage  the  exercise  of  cleanliness  and 
care  of  milk  by  the  producers.  This  need  not  be  worse  than 
at  present  if  inspection  methods  are  thorough.  As  a  matter  of 
fact,  pasteurization  is  not  lessening  the  demands  for  care  in  pro- 
ducing milk.  A  number  of  instances  could  be  pointed  out  of 
dairymen  who  pasteurize  but  keep  the  producers  up  to  a  high 
standard  by  counting  the  bacteria  in  the  milk  and  by  a  private 
inspection  service. 


124  PASTEURIZATION  OF  MILK. 

REFERENCES. 

1.  DOANE  and  PRICE.     The  comparative  digestibility  of  raw,  pasteur- 
ized and  cooked  milk.     Bui.  No.  77,  Maryland  Agr.  Exp.  Sta.,  College 
Park,  Md.,  1901. 

2.  FARRINGTON  and   RUSSELL.      Pasteurization  of  milk  and   cream 
at  140°  F.     Sixteenth  Ann.  Kept.,  Agr.  Exp.  Sta.  Univ.  of  Wis.,  Mad- 
ison, Wis.,  1899,  p.  129. 

3.  FREEMAN.     The  ferments  of  milk  and  their  relation  to  pasteur- 
ization.     Jour.  Amer.  Med.  Assn.,  Vol.  XLJX,  1907,  No.  21,  p.  1740. 

4.  FREEMAN.     Pasteurization  :  The  advantages  and  disadvantages  to 
the  consumer.     N.   Y.  Med.  Jour.,  March  23,  1907. 

5.  HIPPIUS.     Biologisches  zur  Milchpasteurisierung.    Jahrb.  Kinder- 
heilk.,  Bd.  L/XI,  1905,  S.  365. 

6.  JENSEN,  translated  by  LEONARD  PEARSON.     Essentials  of  milk  hy- 
giene, etc.     Philadelphia  :  J.  B.  Lippincott  Company,  1909. 

7.  JENSEN  et  PLATTNER.   De  1'action  du  chauffage  sur  le  lait  de  vache. 
Rev.  Gen.  Lait,  4e  Annee,  1905,  No.  16,  p.  561,  etc. 

8.  L/EDERLE.     Pasteurization  of  milk.     Amer.  Jour.  Pub.  Hyg.,  O. 
S.  Vol.  XVII,  1907,  No.  2,  (N.  S.  Vol.  Ill,  No.  3),  p.  164. 

9.  PARK.      Current  misstatements  and  fallacies  regarding  the  milk 
and  milk  supply    of    New    York    City.       Medical  Record,  Vol.  IvXXI, 
March  23,  1907,  p.  501. 

10.  PRESCOTT.     The  efficiency  of  commercial   pasteurization  and  its 
relation  to  the  milk  problem.      Technol.  Quar.,  Vol.  XVIII,  1905,  No. 
3.  p.  247. 

11.  ROGERS.     The  bacteria  of  pasteurized  and  unpasteurized  milk  un- 
der laboratory  conditions.     Bui.  No.  73,  Bur.  Anim.  Ind.,  ( '.  S.  Dept. 
Agr.,  Washington,  D.  C.,  1905. 

12.  ROSENAU.     Pasteurization.     Bui.  No.  41,  Hyg.  I^ab.,  U.  S.  Pub. 
Health  and  Mar.  Hosp.  Sen'.,  Washington,  D.  C.,  1908,  p.  591. 

13.  ROSENAU.     The  thermal  death  points  of  pathogenic  micro-organ- 
isms in  milk.     Bui.  Aro.  42,  Hyg.  Lab.,  U.  S.  Pub.  Health  and  Mar. 
Hosp.  Serv.,  Washington,  D.  C.,  1908. 

14.  ROTCH.     Pasteurization  of  milk   for   public  sale.     Amer.  Jour. 
Pub.  Hyg.,  O.  S.  Vol.  XVII,  1907,  No.  2,   (N.  S.  Vol.  Ill,  No.  3),  p.  181. 

15.  RUSSELL.     Outlines  of  dairy  bacteriology.     Madison,  Wis.:  H.  L,. 
Russell. 

16.  RUSSELL  and  HASTINGS.     Thermal  death  point  of  tubercle  bacilli 
under  commercial  conditions.     Seventeenth  Ann.  Rept.,  Agr.  Exp.  Sta. 
Univ.  of  Wis.,  Madison,  Wis.,  1900,  p.  147. 


REFERENCES.  125 

17.  RussKLiv  and  HASTINGS.     On  the  increased  resistance  of  bacteria 
in  milk  pasteurized  in  contact  with  air.     Eighteenth  Ann.  kept.,  Agr. 
E.vp.  Sta.  I'nii*.  of  Wis.,  Madison,  Wis.,  1901,  p.  185. 

18.  RUSSKU,  and  HASTINGS.     Effect  of  short  periods  of  exposure  to 
heat  on  tubercle  bacilli  in  milk.      Twenty-first  Ann.  Rept.,  Agr.  Exp. 
Sta.  i'niv.  of  Wis.,  Madison,  Wis.,  1904,  p.  178. 

19.  Russian  and  HOFFMANN.     Bacteriological  examination  of  milk 
pasteurized  in  Miller  apparatus.     Twenty-second  Ann.  Rept.,  Agr.  Exp. 
Sta.   I'niv.  of  Wis.,  Madison,  Wis.,  1905,  p.  236. 

20.  SMITH.     The  thermal  death  point  of  tubercle  bacilli  in  milk  and 
some  other  fluids.     Jour.  E.rpcr.  Med.,  Vol.  IV,  1899,  No.  2,  p.  217. 

21.  SPARGO.     T.he  common  sense  of  the  milk  question.     New  York: 
The  Macmillan  Company,  1908. 


CHAPTER  VII. 


MICROSCOPIC  TESTS  OF  MILK. 


Mammitis  in  the  cow.  Cows  very  frequently  suffer  from 
mammitis  associated  with  the  presence  of  streptococci.  The 
majority  of  dairies  contain  cows  that  show  active  inflammatory 
changes  in  one  or  more  quarters  of  the  udder.  The  abnormal 
product  of  such  an  udder  always  contains  pus  cells  and  strep- 
tococci. Clinical  manifestations  of  the  disease  vary  from  the 
case  exhibiting  marked  swelling  of  the  udder,  with  a  marked 
abnormal  secretion,  down  through  various  gradations  of  clinical 
manifestations  as  exhibited  through  the  condition  of  the  udder 
or  secretion,  to  the  normal  (34).  More  than  this,  bacteri- 
ological study  of  some  apparently  healthy  udders  reveals 
streptococci  in  the  whole  organ  or  in  particular  quarters  of  the 
udder.  Sometimes  in  these  cases'a  history  of  a  previous  attack 
of  mammitis  may  be  established  by  inquiry  or  by  the  discovery 
of  indurated  portions  of  the  udder  by  palpation,  and  other 
times  not. 

Tests  for  cellular  content  of  milk.  The  development  of 
microscopic  tests  of  milk  has  been  actuated  by  a  desire  to 
determine  quickly  which  cows  supplying  city  milk  are  suffer- 
ing from  garget  and  yielding  pus  cells  and  the  accompanying 
organisms  of  suppuration.  The  examination  of  a  large  num- 
ber of  milk  samples  in  a  city  bacteriological  laboratory  by  a 
fairly  rapid,  accurate  method  would  perhaps  obviate  numerous 
visits  to  the  dairies.  In  case  of -positive  results,  the  dairies 
might  be  visited  and  inspected  for  udder  disease  or  the  milk 
of  the  individual  animals  in  turn  examined  by  the  same  test  as 
a  more  delicate  method  than  physical  examination  for  selecting 
those  cows  yielding  pus  cells. 

Stokes'  test.  Stokes  (29)  centrifugalized  10  cc.  of  milk, 
smeared  the  sediment  on  a  cover  glass  and  stained.  When 


TKSTS  1'OK   CKLLULAR   CONTENT  OF  MILK.  127 

upon  microscopic  examination  "  an  excessive  amount  of  pus  " 
was  found  in  a  sample  of  herd  milk  the  examination  of  the 
individual  cows  was  suggested.  The  presence  of  more  than  5 
pus  cells  per  field  of  a  one-twelfth  objective  in  the  milk  of  an 
individual  cow  was  regarded  as  justification  for  the  exclusion  of 
the  cow7  from  the  herd.  The  original  article  describing  the 
test  contained  results  of  the  examination  of  a  series  of  cows, 
one-third  of  which  were  condemned  on  the  basis  of  the  stand- 
ard selected. 

Bergey  (3,  4.  5)  found  it  necessary  to  lower  the  standard 
and  regarded  10  cells  per  field  as  an  indication  of  pus  associ- 
ated with  inflammatory  reaction  of  the  udder  caused  by  pyo- 
genic  organisms. 

Stewart's  test.  Stewart  (28),  of  the  Philadelphia  Bureau  of 
Health,  further  modified  the  method  and  applied  it  to  the 
examination  of  large  numbers  of  samples  of  mixed  herd  milk. 
He  describes  the  apparatus  and  method  as  follows  : 

' '  This  apparatus  consists  of  a  circular  pan  about  12  inches  in  diameter, 
and  -'4 -inch  deep,  containing  twenty  small  glass  tubes.  The  tubes  con- 
tain 1  cc.  of  milk  and  are  filled  by  means  of  a  small  bulb  similar  to  that 
ordinarily  used  on  medicine  droppers.  The  end  of  the  tube  is  closed  by 
a  small  rubber  stopper,  and  the  tubes  are  held  in  the  pan  by  spring 
clamps.  This  pan  is  fitted  upon  the  ordinary  Boekel  •  water  centrifuge 
and  covered  with  a  lid  which  is  held  down  by  a  thumbscrew.  The  pan 
covered  in  this  way  furnishes  a  surface  of  very  slight  resistance  to  the 
atmosphere  during  its  revolution,  somewhat  on  the  principle  of  a  child's 
top. 

' '  By  the  old  method  the  arms  of  the  centrifuge  containing  the  milk 
encountered  so  much  resistance  in  their  revolution  that  the  speed  with 
15  pounds  water  pressure  was  not  more  than  1,200  revolutions  per  minute, 
while  the  speed  obtained  with  the  new  apparatus  is  from  2,500  to  3,000 
revolutions  per  minute  with  15  pounds  pressure.  This  rapid  speed 
causes  sedimentation  to  occur  in  less  than  five  minutes.  When  this  is 
completed  the  centrifuge  pan  can  be  lifted  from  the  motor  and  the  per 
cent,  of  cream  measured  by  a  graduated  scale  marked  upon  the  tube. 
The  heavier  matter,  as  the  insoluble  dirt,  pus  cells  and  bacteria,  is  thrown 
to  t?he  peripheral  end  of  the  tube,  where  it  adheres  to  the  rubber  cork  in 
the  lumen  of  the  tube.  To  examine  this  sediment,  the  cork  is  carefully 
removed  and  a  spread  made  by  rubbing  the  cork  containing  the  sediment 
over  an  area  of  a  square  centimeter  on  a  3-inch  by  6-inch  glass  slide. 
The  proper  area  of  the  smear  is  obtained  by  placing  underneath  the  slide 
a  scale  of  circles  having  an  area  of  a  square  centimeter.  After  the 


128  MICROSCOPIC  TKSTS  OF  MILK. 

smears  are  dried  in  air  without  fixation  by  heat,  the  preparation  is  stained 
with  the  Jenner  blood  stain  for  two  minutes,  keeping  the  stain  in  con- 
stant motion.  The  excess  of  stain  is  washed  off  in  water,  and  the  prep- 
aration is  dried  in  air.  By  this  blood-staining  method,  the  pus  and  blood 
cells  are  stained  perfectly,  and  the  ordinary  microorganisms  take  the  blue 
stain  well. 

"The  stained  specimens  are  examined  with  a  one-twelfth  Leitx.  objec- 
tive and  a  No.  3  eye-piece.  The  character  of  the  bacteria  is  noted,  and 
the  average  number  of  pus  cells  per  field  is  counted.  This  average  num- 
ber is  multiplied  by  4,400,  since  there  are  about  4,400  fields  to  a  square 
centimeter,  as  estimated  by  the  stage  micrometer.  This  result  is  approxi- 
mately the  number  of  pus  cells  per  cubic  centimeter  of  milk." 

When  a  sample  of  milk  showed  over  100,000  cells  per  cc., 
or  showed  "streptococci  and  the  ordinary  pus  producing  organ- 
isms," an  examination  of  the  herd  was  ordered.  Stewart 
gave  figures  showing  that  inspections  of  condemned  herds  by 
veterinarians,  revealed  diseased  animals  in  those  herds. 

The  quantitative  features  of  the  test  have  not  been  found 
accurate.  The  average  percentage  variations  between  dupli- 
cate determinations  have  been  found  to  be  112%  in  a  series  of 
-23  determinations  made  by  Russell  and  Hoffmann  (23,  24). 
The  present  writer  and  associates  (32)  also  noted  its  very  unsat- 
isfactory behavior.  The  numerical  results  are  always  very 
much  below  the  true  number  present  and  bear  no  constant 
ratio  to  the  true  number. 

The  test  very  rarely  indicates  the  presence  of  streptococci, 
even  though  streptococci  are  proven  by  other  methods  to  be 
very  common  in  the  milk.  The  presence  of  insoluble  detritis, 
blood,  etc.,  is  indicated  by  the  test. 

Slack's  test.  Slack  (26)  modified  the  Stewart  method  by 
using  tubes  of  a  larger  bore  containing  2  cc.,  and  smeared  the 
sediment  over  4  square  centimeters.  He  further  lowered  the 
standard  to  50  cells  or  over  per  one-twelfth  oil  immersion  field, 
as  warranting  the  condemnation  of  milk.  When  streptococci 
are  found  in  the  sediment,  he  condemns  for  them  alone  if  these 
three  conditions  are  fulfilled  : 

1.  Microscopic  examination  of  sediment  shows  streptococci, 
diplococci,  or  cocci. 


,    TESTS  FOR  CELLULAR  CONTENT  OF  MILK.  129 

2.  A  plate  culture  shows  colonies  resembling  those  of  strep- 
tococci, in  excess  of  100,000  per  cc. 

3.  From  ten  to  fifty  of  the  colonies  are  transferred  to  broth 
and  grown  24  hours  at  37 °C.  after  which  the  broth  cultures 
show  streptococci  alone  or  in  great  excess  of  other  bacteria 
present. 

Slack  utilizes  the  test  also  for  the  direct  microscopic  esti- 
mation of  the  number  of  bacteria  present. 

Doane- Buckley  test.  Doane  and  Buckley  (10)  have  devised 
a  test  which  has  been  somewhat  improved  upon  by  Russell  and 
Hoffmann  (8).  The  technic  given  below  is  that  described  by 
the  latter  writers  : 

COLLECTION  OF  SAMPLE. 

Sample  for  analysis  should  be  taken  from  the  entire  milking  of  the 
animal,  as  the  stoppings  contain  a  somewhat  larger  number  of  cells  than 
other  portions  of  the  milk.  For  the  purpose  of  examination  take  200  cc. 
in  stoppered  bottle. 

TIME  INTERVAL,  BETWEEN  COLLECTION  AND  ANALYSIS. 

To  secure  satisfactory  results,  milk  must  be  examined  in  a  sweet  con- 
dition. Development  of  acidity  tends  to  precipitate  casein  in  the  milk, 
and  thus  obscure  the  examination  of  microscopical  preparations.  Sam- 
ples received  from  a  distance  can  be  preserved  for  satisfactory  microscop- 
ical examination  by  the  addition  of  formalin  at  time  of  collection, — 
proportion  of  1  cc.  to  250  cc.  of  milk.  Formalin  has  been  found  the  best 
preservative  to  use,  although  it  causes  contraction  of  the  cells  to  some 
extent. 

PROCEDURE  WITH  REFERENCE  TO  PREPARATION  OF  SAMPLE. 

1.  HEATING  SAMPLE. 

To  secure  the  complete  sedimentation  of  the  cellular  elements  in  the 
milk,  it  is  necessary  to  heat  the  same  to  a  temperature  which  will  break 
down  the  fat  globule  clusters,  or  lessen  the  ordinary  creaming  properties 
of  the  milk.  Samples  should  be  heated  at  65°  to  70°  C.  for  not  less  than 
ten  minutes,  or  from  80°  to  85°  where  very  short  periods  of  exposure 
(one  minute)  are  given.  This  treatment  causes  the  more  homogeneous 
distribution  of  the  fat  globules  through  the  milk,  and  when  the  sample 
is  then  subjected  to  centrifugal  force  the  cell  elements  are  not  caught  in 
the  rising  fat  globules,  but  on  account  of  their  higher  specific  gravity  are 
concentrated  in  the  sediment  by  centrifugal  force. 


130  MICROSCOPIC  TESTS  OF  MILK. 

2.  CONCENTRATION  OF  CEI,U*LAR  KI.KMKNTS. 

Ten  cc.  of  milk  are  placed  in  an  ordinary  sedimentation  tube,  and  after 
heating  as  above  directed,  and  subsequently  shaking,  the  milk  is  centri- 
fugalized  twenty  minutes  at  1,200  revolutions  per  minute.  A  hand 
centrifuge  may  be  employed  for  this  purpose,  but  where  available  a  steam 
turbine  Babcock  milk  tester  may  be  found  more  practicable. 

Note. — This  speed,  maintained  for  the  time  mentioned,  is  sufficient  to 
sediment  practically  all  the  cell  elements  suspended  in  the  milk.  In  our 
experience  we  have  found  the  number  of  cells  in  supernatant  milk  to 
average  only  3)4  per  cent. 

3.  PREPARING  THE  SAMPLE  FOR  EXAMINATION. 

After  centrifugalizing,  the  cream  and  the  supernatant  milk  are  removed, 
with  the  exception  of  the  last  half  cc.  by  aspirating  with  an  exhaust  pump 
and  wiping  the  walls  of  the  tube' with  a  cotton  swab.  After  thoroughly 
mixing  the  sediment  with  a  glass  rod,  enough  of  the  emulsion  is  placed 
in  an  ordinary  blood  counter  (Thoma-Zeiss  pattern)  to  fill  exactly  the 
cell.  The  preparation  is  then  allowed  to  stand  for  a  minute  or  two  to 
permit  the  cellular  elements  to  settle  to  the  bottom  of  the  cell,  while  the 
few  fat  globules  in  the  liquid  rise  to  the  surface.  This  method  permits 
of  the  differentiation  of  the  cells  from  the  small  fat  globules,  so  that  a 
distinct  microscopic  observation  can  be  made. 

EXAMINATION  OF  MATERIAL. 

The  preparation  is  examined  in  an  unstained  condition. 

NOTE. — Most  observers  have  usually  stained  the  sediment  prior  to  ex- 
amination, but  we  have  found  with  the  above  treatment  that  the  cells 
may  be  enumerated  quite  as  well  in  an  unstained  as  a  stained  condition. 

The  count  is  made  wTith  a  1-inch  eve-piece  and  |  objective.  Where  the 
number  of  cell  elements  exceeds  12  or  15  per  microscopic  field,  above 
referred  to,  one-fourth  of  the  entire  ruled  area  of  the  counter,  equivalent 
to  100  of  the  smallest  squares  of  the  cell,  are  counted.  Where  the  cell 
elements  are  less  abundant,  one-half  of  the  cells  in  the  entire  area  (two 
to  four  hundred  squares)  are  enumerated.  The  average  number  of  the 
cells  per  smallest  square  is  then  obtained,  which,  when  multiplied  by 
200,000,  gives  the  number  of  cells  per  cubic  centimeter  in  the  original 
milk.  (If  multiplied  by  4, 000, 000,  we  have  the  number  of  cells  per  cubic 
centimeter  in  the  sediment  examined.  As  the  sediment  represents  the 
concentration  of  the  cells  into  one-twentieth  of  the  original  volume  of 
milk  taken,  10  cc.  to  one-half  cc.,  this  number  should  be  divided  by  20 
to  give  the  number  of  cells  per  cubic  centimeter  in  the  original  milk.) 

NOTE. — The  above  factor  of  4, 000, 000  is  obtained  as  follows:  The  cubic 
content  of  the  blood  counter  represents  one-tenth  of  a  cubic  centimeter. 
This  volume  is  divided  by  means  of  the  ruled  scale  into  400  small  cubes, 
each  equal  to  one  four-thousandth  of  a  cubic  millimeter,  or  one  four- 
millionth  of  a  cubic  centimeter. 


TKSTS   I.'OK    CKI,UTI,AR    COXTKNT  OT   MILK.  131 


All  results  should  he  expressed  in  nunihers  of  cells  per  cubic  centime- 
ter of  the  original  milk,  and  'in  order  to  avoid  fictitious  accuracy,  should 
he  given  in  accordance  with  the  method  adopted  hy  the  Committee  on 
Standard  Methods  of  Water  Analysis,  as  reported  in  this  Committee's 
report  to  the  Laboratory  vSection  of  the  American  Public  Health  Associa- 
tion for  1905,  page  94. 

The  test  has  been  shown  to  give  results,  on  duplicate  deter- 
minations, with  a  percentage  variation  of  only  about  6%  (23). 
Thus  we  have  a  test  of  excellent  precision  that  already  has 
added  valuable  facts  to  the  knowledge  of  the  subject  of  leu- 
cocytes in  milk. 

The  test  has  not  been  widely  applied  in  practice,  because  of 
the  difficulty  in  formulating  a  standard.  A  cellular  content 
varying  from  100,000  to  400,000  per  cc.  is  common  in  normal 
cows,  and  even  counts  of  1,000,000  per  cc.  are  encountered. 
A  series  of  determinations  of  the  leucocytes  in  the  milk  of  102 
healthy  cows  showed  an  average  of  241,000  per  cc.  This 
range  of  counts  considerably  overlaps  the  range  of  counts  ex- 
hibited by  cows  with  noticeable  udder  trouble. 

Under  the  circumstances,  the  milk  of  a  diseased  cow  with  a 
count  of  a  few  millions  is  so  diluted  in  the  milk  of  the  healthy 
cows  showing  relatively  high  counts,  that  the  leucocyte  con- 
tent of  the  mixed  milk  is  not  raised. 

Savage  s  test.  Savage  (25)  has  developed  a  very  similar  test. 
One  cc.  of  milk  is  diluted  with  20  cc.  of  Toisson's  fluid  and 
centrifugalized  for  ten  minutes  at  about  1,800  revolutions  per 
minute.  The  cream  is  then  agitated  with  a  glass  rod  and  the 
whole  again  centrifugalized  for  ten  minutes,  and  the  super- 
natant fluid  is  drawn  off  to  the  1  cc.  mark.  The  remaining 
1  cc.  is  thoroughly  mixed  and  the  number  of  leucocytes  deter- 
mined by  the  use  of  the  Thoma-Zeiss  blood  counter.  This, 
like  the  Doane-Buckley  test,  shows  high  numbers  of  leucocytes, 
and  the  same  difficulties  in  setting  a  standard  are  encountered. 

Trommsdorjf  s  test.  Trommsdorff  (22,  30,  31)  arrives  at  con- 
clusions regarding  the  number  of  cells  in  milk  by  measuring  the 
amount  of  sediment  obtained  by  centrifugalizing.  Five  cc.  of 
mixed  milk  is  centrifugalized  for  some  minutes  at  1,200  revolu- 


132  MICROSCOPIC  TEvSTS  OF  MILK.- 

tions,  and  the  amount  of  sediment  is  noted.  For  this  purpose 
there  is  used  a  special  centrifuge  tube  with  the  bottom  drawn 
out  into  a  capillary  tube,  properly  graduated.  These  tubes  are 
prepared  by  Franz  Hugershoff,  Leipzig. 

The  mixed  milk  of  cows  with  sound  udders,  as  a  rule,  shows 
sediment  varying  from  traces  to  .5  cc.  per  liter,  with  1  cc. 
per  liter  as  the  maximum.  On  the  basis  of  the  examination 
of  hundreds  of  mixed  milk  samples,  it  is  asserted  that  when 
the  test  gives  over  1  vol.  per  mille,  it  can  be  shown  that  one 
or  more  quarters  of  the  udders  of  the  cows  are  giving  milk 
with  an  excessive  number  of  cells. 

The  test  is  recommended  by  Trommsdorff  as  an  aid  in  the 
diagnosis  of  chronic  mammitis.  He  applied  it  to  the  individ- 
ual cows  in  a  dairy  of  good  reputation  producing  milk  for 
infant  feeding.  On  three  different  occasions  within  a  period 
of  four  months,  he  designated  as  diseased  20 f/c  on  first  test, 
34.2%  the  second,  and  27%  on  the  third  examination.  The 
number  of  co\vs  tested  on  the  three  occasions  varied  from  35 
to  38.  In  another  dairy  of  66,  12%  were  considered  diseased; 
in  another  of  75,  4%;  and  in  another  of  82  cows,  19.5'/v  . 

The  test  is  said  to  give  identical  results  from  duplicate  de- 
terminations. The  criticism  has  been  made  that  it  is  a  meas- 
ure not  merely  of  leucocytes,  but  also  of  all  substances  that 
might  be  centrifugalized  down  into  a  sediment. 

Significance  of  results.  There  has  been  a  wide  variation  in 
the  amount  of  importance  that  has  been  attached  to  the  results 
of  these  tests.  In  some  cases  their  tentative  nature  has  been 
very  properly  recognized  and  the  results  used  as  indication  of 
the  desirability  of  an  examination  of  the  udders  of  the  cow\s. 

But  instances  are  not  rare  of  cases  where  the  milk  of  a  dealer 
has  been  publicly  condemned  on  the  ground  of  its  containing 
pus,  staphylococci  and  streptococci.  There  are  instances,  too, 
where  the  tests  have  been  applied  to  the  individual  cows  of 
dairies.  Excessive  and  unreasonable  numbers  of  cows  have 
been  condemned  on  the  basis  of  the  results  \vhere  no  symptoms 
of  mammitis  have  been  present.  The  condemnation  of  the 
'  majority  of  the  cattle  in  a  herd  certainly  focusses  attention 
upon  the  evidence  warranting  such  a  procedure. 


SIGNIFICANCE  OK  RESULTS.  133 

The  study  of  the  subject  has  proceeded  in  the  wrong  order. 
The  abnormal  has  been  studied,  tests  devised  and  standards 
set,  all  from  that  standpoint.  The  use  of  checks  to  prove  the 
value  of  tests  has  been  too  frequently  disregarded.  For  in- 
stance, tests  have  been  advocated  as  of  value  in  detecting  the 
location  of  diseased  animals,  without  evidence  being  brought 
forward  to  show  that  the  test  has  been  tried  on  a  group  of 
animals  known  to  be  diseased.  The  detection  of  diseased  ani- 
mals in  the  herds  supplying  condemned  milk  has  been  accepted 
as  confirmation  of  the  value  of  a  test. 

The  work  has  resulted  in  directing  attention  to  the  normal, 
which  has  often  been  too  little  considered.  At  present,  the 
matter  is  in  that  period  of  development  in  which  the  fairness 
of  standards  and  the  accuracy  of  tests  are  being  scrutinized. 
In  judging  the  merits  of  the  various  tests,  a  number  of  facts 
concerning  the  normal  must  be  considered. 

Streptococci  in  milk  Examination  of  samples  of  market  milk 
will  show  streptococci  in  a  very  large  percentage  of  the  cases 
(13,  14,  15,  16,  19).  Heinemann  has  asserted  that  "Bacillus 
acidi  lactici  is  a  myth,"  and  that  the  common  organism  sour- 
ing milk  should  be  called  Streptococcus  lacticus. 

Reference  has  already  been  made  in  Chap.  I  to  the  fact  that 
an  apparently  healthy  cow  was  found  to  harbor  a  pathogenic 
streptococcus  in  the  udder  for  a  considerable  period  of  time. 
In  consequence  the  animal  might  well  be  called  a  streptococ- 
cus carrier  (21). 

There  are  no  generally  accepted  methods  for  differentiating 
the  various  species  of  the  genus  streptococcus  found  in  milk. 
It  cannot  at  present  be  determined  whether  a  given  strepto- 
coccus is  of  human  or  animal  origin,  virulent  or  not,  or  whether 
it  is  a  saprophyte.  Hemolysis  and  agglutination  have  both 
failed  to  yield  conclusive  results  (12)  .  This  group  has  been  the 
despair  of  the  systematists.  Winslow  and  Winslow  (33)  give 
a  valuable  chapter  upon  streptococci. 

Least  of  all,  is  it  possible  to  make  a  differentiation  on  mor- 
phological grounds  alone.  Our  ideas  of  the  hygienic  signifi- 
cance of  the  presence  of  streptococci,  based  on  their  rare 
discovery  by  certain  tests,  must  be  revised. 


134 


MICROSCOPIC  TESTS  OF  MILK. 


Micrococci  in  milk.  Micrococci  (staphylococci) ,  indistin- 
guishable from  Micrococcus  fjyogcucs,  varieties  aurcus  and  albus, 
are  normal  inhabitants  of  the  udder.  Consequently,  they  are 
almost  the  characteristic  organisms  in  the  bacterial  flora  of 
fresh  milk.  Their  close  relationship  to  M.  pyogencs  aurcus 
has  been  determined  by  thorough  systematic  study.  They 
have  been  reported  under  this  name  by  numerous  observers, 
as  noted  in  Chap.  I. 

The  practice  of  reporting  on  the  presence  of  pyogenic  micro- 
cocci  in  centrifugalized  sediments,  from  microscopic  examin- 
ation, is  certainly  not  justified. 

Leucocytes  in  milk.  Polymorphonuclear  leucocytes  may  be 
demonstrated  in  the  milk  of  any  cow  and  must  be  regarded  as 
a  normal  constituent  of  milk.  As  many  as  200,000  per  cc.  in 
the  milk  of  a  cow  may  be  considered  common,  and  500,000 
per  cc.  not  at  all  unusual.  Sprague  (9,  27)  found  the  greatest 


Fig.  15 .     Section  of  udder  shoeing  epithelial  celts. 

a.  Epithelial  cell  7chich  has  become  loosened  from  the  duct  and  is  ready 
to  be  carried  out.  b.  Secreting  epithelial  cell  in  ica/l  of  duct .  a  and  b 
are  of  the  same  structure. 


SIGNIFICANCE  OF  RESULTS.  135 


Fig.  16.  Section  of  udder  showing  epithelial  cells  and  polvnnclear 
leucocytes. 

a .  /-'.pit  he!  ia  I  ce!!  which  has  become  loosened  from  the  wall  of  the  duct, 
similar  to  a  in  Fig.  15 .  b.  Secreting  epithelial  cell  in  situ,  being  same 
in  st nt dii re  as  a.  c.  Polynuclear  leucocytes  in  ducts  ready  to  be  thrown 
out  along  with  the  loose  epithelial  cells. 

variation  among  the  cows  of  a  herd  examined  by  him.  Some 
of  the  apparently  healthy  cows  gave  counts  exceeding  500,000 
per  cc.  It  was  not  possible,  however,  to  pick  ten  cows  that 
would  average  more  than  that  number.  The  leucocyte  count 
of  the  milk  of  two  apparently  healthy  cows  was  determined 
twice  a  day  over  a  long  period  of  time,  and  the  most  abrupt 
fluctuations  were  observed  in  the  number  of  leucocytes  present. 
Heated  milk  gives  a  much  higher  leucocyte  count  by  both 
the  Doane-Buckley  and  the  smeared-sediment  method  (9). 
Leucocytes  and  pus  cells  are  identical,  although  common 
practice  has  determined  that,  under  conditions  of  health,  the 
cells  in  question  shall  be  called  leucocytes,  and  pus  cells  in 
certain  pathological  conditions.  We  have  no  satisfactory 
standard  at  present  to  determine  when  this  change  in  designa- 


136  MICROSCOPIC  TESTS  OF  MILK. 

tion  shall  occur  in  the  case  of  cells  in  milk.  It  has  been  sug- 
gested that  this  should  be  governed  by  the  presence  of  strep- 
tococci, or  fibrin,  or  red  blood  corpuscles  with  the  cells  in 
centrifugalized  sediments.  Besides  the  polymorphonuclears, 
there  may  be  demonstrated  in  milk  sediments  large  and  small 
mononuclears  and  eosinophiles.  Our  knowledge  of  the  source 
of  these  cells  is  incomplete  as  yet.  Boynton  and  Russell  inde- 
pendently have  photographed  sections  of  the  functional,  healthy 
udder,  and  by  this  means  have  shown  the  presence  of  leuco- 
cytes and  other  cells  in  the  lumina  of  the  lactiferous  ducts  in 
contact  with  the  epithelium.  Those  by  Boynton  appear  in 
Figs.  15  and  16.  Very  likely  in  connection  with  milk  secretion 
epithelial  debris  is  extruded  in  milk,  even  though  the  present 
trend  of  opinion  denies  that  fat  secretion  is  accomplished  by 
fatty  degeneration  with  the  destruction  of  the  cell  (l,  2). 
The  general  leucocyte  content  of  the  blood  of  the  cow  seems  to 
bear  no  relation  to  the  leucocyte  count  of  the  milk  (8). 

The  centrifugalized  sediment  of  milk  has  been  known  since 
the  advent  of  the  cream  separator  under  the  name  of  separator 
slime.  The  mass  always  collecting  in  the  bowl  of  the  separator 
has  a  disgusting  appearance  suggesting  pus.  On  this  account 
soriie  dealers  clarify  their  milk,  that  is,  run  it  through  a  separator 
to  remove  this  sediment  and  particles  of  foreign  material.  Here 
again  is  a  case  where  a  normal  milk  constituent  has  had  its 
sanitary  significance  overrated,  because  defective  tests  ordi- 
narily showed  it  to  be  present  in  small  quantity. 

Summary.  Mammitis  is  very  common  among  cows.  The 
majority  of  dairies  contain  cows  that  show  active  inflamma- 
tory changes  in  the  udder,  or  evidence  of  previous  manifesta- 
tions in  the  shape  of  indurations  which  might  warrant  the  diag- 
nosis of  chronic  mammitis.  The  discovery  of  diseased  udders 
in  a  herd  after  the  condemnation  of  the  mixed  milk  by  some 
test  is  therefore  a  fact  of  questionable  significance  in  proving 
the  value  of  the  test. 

In  view  of  all  these  circumstances,  it  cannot  be  said  that 
the  matter  of  microscopic  tests  for  cells  in  milk  is  yet  on  a 
satisfactory  basis.  Future  work  must  be  done  on  individual 
cows  in  determining  the  border  line  between  health  and  disease. 


SUMMARY.  137 

It  would  be  well  to  study  the  milk  of  individual  cows,  prefer- 
ably with  known  histories,  with  reference  to  the  occurrence  of 
leucocytes  and  streptococci.  For  leucocytes  the  Doane- Buck- 
ley test  might  be  used,  and  for  streptococci,  numerical  deter- 
minations. Histological  examination  of  the  udder  may  prove 
to  be  a  reliable  criterion  for  the  determination  of  disease  in 
experimental  work. 

The  situation  is  very  well  summed  up  in  the  Preliminary 
Statement  by  the  Committee  on  Standard  Methods  of  Bacterial 
Milk  Analysis  to  the  Laboratory  Section  of  the  American  Pub- 
lic Health  Association,  in  these  words  : 

"Since,  however,  evidence  already  collected,  warrants  beyond  all 
question  the  general  statement  that  these  cells  frequently  do  not  have  the 
significance  that  has  been  attached  to  them  by  many  observers,  it  would 
perhaps  be  more  fair  to  all  parties  concerned  to  use  this  (leucocyte)  test 
at  present  as  a  means  of  detection  only,  and  not  to  condemn  the  supply 
unless  physical  lesions  are  demonstrated.  The  standards  so  far 

chosen  have  been  more  or  less  arbitrarily  selected  on  what  appears  as 
rather  inadequate  data,  and  from  a  comparison  of  results  it  is  apparent 
that  much  more  comparative  work  needs  to  be  done."  (8) 

The  committee  expresses*  a  similar  view  in  its  1908  report  as 
follows  : 

' '  It  is  the  opinion  of  the  Committee  that  milks  having  high  leucocyte 
content,  unless  accompanied  by  other  indications  of  inflammation  such 
as  blood  or  virulent  organisms,  should  not  be  condemned  as  unfit  for  use 
on  the  laboratory  findings  alone.  Such  milks  may  be  regarded  with  sus- 
picion and  the  laboratory  findings  may  well  serve  as  a  guide  for  veteri- 
nary inspection. "  (9) 

The  writer  rather  doubts  whether  microscopic  examination 
of  milk  will  eventually  prove  a  satisfactory  means  of  protect- 
ing the  public  from  streptococci  in  milk  from  diseased  cows. 
When  a  satisfactory  decision  has  been  reached  as  to  wrhat  con- 
stitutes a  diseased  udder  in  a  cow  and  how  to  detect  the  pres- 
ence in  a  herd  of  animals  so  affected,  there  remain  administrative 
difficulties.  The  individuals  in  a  dairy  herd  are  constantly 
changing  and  the  health  of  the  udder  is  liable  to  variation  from 
day  to  day,  which  necessitates  very  frequent  examinations. 
Then  there  remains  the  difficulty  of  enforcing  the  exclusion  of 
the  milk  of  the  condemned  cow.  A  large  American  city  of  to- 


138  MICROSCOPIC  TESTS  OF  MILK. 

day  is  indeed  fortunate  if  it  has  a  corps  of  inspectors  sufficient 
to  permit  visiting  each  dairy  four  times  a  year.  The  conditions 
existing  and  the  difficulties  of  correcting  them  by  inspection, 
lead  one  to  doubt  whether  anything  but  pasteurization  can 
give  effective  protection  from  streptococci. 

Bloody  milk.  Slight  injuries  to  the  udder  will  sometimes 
cause  the  rupture  of  a  blood  vessel  and  result  in  the  mixing  of 
blood  with  the  milk.  The  blood  may  be  so  small  in  amount 
as  to  escape  notice  by  the  milker.  After  delivery,  when  the 
cream  rises,  it  will  be  distinctly  pink.  Microscopic  examina- 
tion of  the  cream  will  reveal  red  blood  corpuscles.  To  detect 
the  source  of  such  milk,  it  maybe  necessary  to  collect  a  sample 
from  each  quarter  of  each  cow's  udder,  in  separate  test  tubes. 
The  bloody  sample  may  be  detected  in  the  test,  tube  immedi- 
ately after  drawing,  or  certainly  later  after  the  cream  has  risen. 


REFERENCES. 

1.  ARNOLD.     Die  Bedeutung  der  Fettsynthese,  Fettphagocytose,  Fett- 
sekretion  und  Fettdegeneration  fur  die  Milch-  und  Kolostrumbildun.^. 
Munch.. Med.   irc/nischr.,  52.  Jahrg.,  No.  18,  1905,  S.  841. 

2.  ARNOLD.       The  morphology    of    milk    and    colostrum    secretion. 
Beitr.  Path.  Anat.  u.  Allg.  Path.,   Bd.  XXXVIII,  1905,   No.  2,   S.  421. 
Abs.  in  Exp.  Sta.  Rec.,  Vol.  XVII,  p.  495. 

3.  BRRGKY.     An  investigation  on  the  value  of  certain  sanitary  and 
other  precautionary  measures,  employed  in  the  protection  and  marketing 
of  milk,  upon   the  bacterial   contents  of  the  milk.     l^nn.  Dept.  Agr. 
Kept.,  1900,  Part  I,  p.  133. 

4.  BERGEY.     The  cellular  and  bacterial  content  of  cow's  milk  at  dif- 
ferent periods  of  lactation.       Univ.  Penn.  3 fed.  />'///.,  Vol.  XVII,  July- 
August,  1904,  p.  181. 

5.  BERGEY.     The  source  and  nature  of  bacteria  in  milk.     /////.  ,V<;. 
125,  Penn.  Dept.  Agr.,  1904. 

6.  BERGEY.     The  leucocyte  and  streptococcus  content  of  cow's  milk. 
I 'uh'.  Penn.  JAY/.  /;«/.,  September,  1907. 

7.  BRUNING.      Investigations  of  market  milk  in 'Leipzig  with  special 
reference  to  the  presence  of  streptococci.    Jahrb.  Kindcrheilk.    Bd.  L,XII, 
1905,   No.  1,   S.  1.      Abst.  in  E.vp.  Sta.  Rec.,  Vol.  XVII,    1906,   No.  5, 
p.  496. 


REFERENCES.  139 

8.  COMMITTEE    OF    THH     IVA  HOKATOKV    SECTION    OF    THE     AMERICAN 

I't 'HIJC  IlEAi/rii  ASSOCIATION.  Preliminary  statement  by  the  committee 
on  standard  methods  of  bacterial  milk  analysis.  Amer.  Join-,  /'nh. 
Hyg.,  Vol.  XVII,  1907,  No.  4,  N.  S.  Vol.  Ill,  No.  5,  p.  331. 

9.  COMMITTEE    OF    THE    LABORATORY    SECTION    OF    THE    AMERICAN 

Prmjc  HEALTH  ASSOCIATON.     Report  of  progress,  1908.     Unpublished. 

10.  DOAXE.     Leucocytes  in  milk  and  their  significance.      Bui.  No. 
102,  Maryland  A^r.   /<;.r/>.  .S/tf.,  College  Park,  Md.,  1905. 

11.  FLYNN.     Beitrag /Air  Kenntniss  der   Milch.     Ccntbl.   ttakt,  etc., 
2.  Abt.,  Bd.  XVIII,  1907,  S.  428. 

12.  HARRIS.     The  relative  importance  of  streptococci  and  leucocytes 
in  milk.     Jour.  Infect.  Diseases,  1907,  Supp.  No.  3,  p.  50. 

13.  HEIXEMAXX.     The  significance  of  streptococci  in  milk.      Jour. 
Infect.  Diseases,  Vol.  Ill,  1906,  No.  2,  p.  173. 

14.  HEINEMANN.     The  pathogenicity  of  streptococcus  lacticus.  Jour. 
Infect.  Diseases,  Vol.  IV,  1907,  No.  1,  p.  87. 

15.  HOUSTON.     The  bacteriological  examination  of  milk.    Jour.  Corn. 
l\ith.  and  Ther.,  Vol.  XIX,  1906,  p.  145. 

16.  KAISKR.     On  the  streptococci  in  milk.      Arch.  Hyg.,   Vol.  LVI, 
1906,  No.  1,  p.  2. 

17.  KUNTZE.     (iewinnung  keimarmer  Milch.     Centbl .  J>akt.,  etc,  2. 
Abt.,  Bd.  XX,  1907-08,  S.  420. 

18.  MIIJ,KR.     The  significance  of  leucocytes  in  milk.     flu/.  Xo.  41, 
Hyjf.  Lab.,  {'.  S.  Pub.  Health  and  Mar.  Hosp.  Sen'.,  Washington,  D.C., 
1908,  p.  479. 

19.  MrijjvR.     On  the  streptococci  in  milk.     Arch.  Hy^.,  Vol.  L/VI, 

1906,  No.  1,  p.  90.     Abst.  in  E.vp.  Sta.  Kec.,  Vol.  X\'II,  1906,  No.  12, 
p.  1183. 

20.  PENNINGTON  and  ROBERTS.     The  significance  of  leucocytes  and 
streptococci  in  the  production  of  a  high  grade  milk.     Jour.  Infect.  Dis- 
eases, Vol.  V,  1908,  No.  1,  p.  72. 

21 .  REED  and  WARD.     The  significance  of  the  presence  of   strepto- 
cocci in  market  milk.     Amer.  Med.,  Vol.  V,  1903,  No.  7,  p.  256. 

22.  Rriyi,MAN  und  TROMMSDORFF.     Milchhygienische  Untersuchun- 
gen.     Arch.  Hyg.,  Bd.  UX,  3.  Heft.,  1906,  S.  224. 

23.  RrssEU,  and  HOFFMANN.     Leucocyte  standards  and  the  leucocyte 
content  of  milk  from  apparently  healthy  cows.     Jour.  Infect.  Diseases, 

1907,  Supp.  No.  3,  p.  63. 

24.  RrssKUv  and  HOFFMANN.     Distribution  of  cell  elements  in  milk 
and  their   relation   to  sanitary   standards.       Ttijenty-fourth   Ann.  l\epi. 
Agr.  E*p.  Sla.,  ('nil',  of  Wis.,  Madison,  Wis.,  1907,  p.  231. 


140  MICROSCOPIC  TESTS  OF  MILK. 

25.  SAVAGE.      Streptococci    and    leucocytes    in    milk.      Jour.   Hyg. 
(Cambridge),  Vol.  VI,  1906,  No.  2,  p.  123. 

26.  SLACK.     Methods  of  bacteriological  examination  of  milk.     Jour. 
Infect.  Diseases,  Supp.  No.  2,  February,  1906,  p.  214. 

27.  SPRAGUE.     The  leucocyte  content  of  milk,     /in I.  I  7.  State  Hoard 
of  Health,  Vol.  IX.  No.  1.  1908,  p.  44. 

28.  STEWART.     Methods  employed  in  the  examination  of  milk  by  city 
authorities.     Amcr.  J/«/.,  Vol.  IX,  1905,  No.  12,  p.  486. 

29.  STOKES.      The  microscopic  examination  of    milk.      Ann.   Kept. 
Health  Dept.  Baltimore,  1897,  p.  105. 

30.  TROMMSDORFF.     Munchen.  Jfed.  II  'chnschr,,  1906,  No.  12,  S.  541. 

31.  TROMMSDORFF.     Xeue  Methode  /.ur   Diagnose  der  chronischen, 
speziell  der  Streptokokenmastitis  der  Kuh.     Berlin  Tierarztl.  \Vchnschr., 
1906,  Xo.  15,  S.  281. 

32.  WARD,  HENDERSON  and  HARING.     The  numerical  determination 
of  leucocytes  in  milk.    Nineteenth  Biennial  Kept .  Cal.  State  Bd.  Health, 
1906,  p.  142. 

33.  WINSLOW  and   WIN-SLOW.     The   systematic   relationships  of  the 
coccaceae.     Xew  York  :  John  Wiley  and  Sons.     1908. 

34.  ZSCHOKKE,  transl.  by  WARD.     Experiments  in  treating  infectious 

mammitis  in  the  cow.     Am.   I'et.  Rei'.,  Vol.  XXV,  1901,  Xo.  1,  p.  9. 


CHAPTER  VIII. 


BACTERIOLOGICAL  EXAMINATION  OF  MILK. 


Numerical  determination  of  bacteria.  The  diversity  of 
methods  in  use  in  different  laboratories  is  such  that  compari- 
son of  the  numerical  results  obtained  by  them  is  quite  out  of 
the  question.  The  water  bacteriologists  long  ago  recognized 
the  undesirability  of  a  diversity  of  methods  in  counting  bac- 
teria in  water,  and  applied  a  remedy.  The  standard  methods 
of  water  analysis  suggested  by  the  committee  of  the  American 
Public  Health  Association  have  been  favorably  received.  The 
results  warrant  and  encourage  further  work  towards  the  unifi- 
cation of  other  laboratory  methods.  A  committee  of  the  Lab- 
oratory Section  of  the  American  Public  Health  Association 
has  in  hand  the  task  of  formulating  standard  methods  of  bac- 
terial milk  analysis.  The  committee,  consisting  of  F.  H.  Slack, 
chairman  ;  W.  H.  Park,  E.  C.  Levy,  F.  C.  Harrison,  C.  E. 
Marshall  and  H.  Iv.  Russell,  has  been  at  work  for  two  years, 
weighing  the  merits  of  the  various  methods  in  use.  There 
have  been  submitted  two  preliminary  reports,  one  in  1907  and 
one  in  1908  (3,  4).  The  methods  reported  are  not  definitely 
selected  as  a  final  standard,  but  represent  a  consensus  of  opinion 
of  American  workers  on  the  subject.  The  methods  for  the 
numerical  determination  of  bacteria  herewith  recommended 
are  a  composite  of  the  two  reports  of  the  A.  P.  H.  A.  Com- 
mittee. The  recommendations  are  substantially  as  made  in 
the  1907  report,  and  the  modifications  made  in  1908  are  intro- 
duced and  so  indicated. 

NUMERICAL  DETERMINATION  OF  BACTERIA. 

There  is  no  method  known  by  which  the  exact  number  of  bacteria 
in  a  sample  of  milk  may  be  determined,  and  even  when  the  best  methods 


142  HACTKKIOI.OC1ICAI.   EXAMINATION  OF  MILK. 

are  used,    the  count  is  always  less   than    the   actual   number  of  bacteria 
present,  for  the  following  reasons  : 

(«)  Many  bacteria  in  process  of  multiplication  are  held  together  bv 
aclhesive  membranes  in  pairs,  chains  or  masses.  It  is  for  the  purpose  of 
separating  bacteria  thus  joined,  as  well  as  to  obtain  an  even  mixture, 
that  the  sample  itself  and  the  diluted  sample  when  plating  are  shaken. 
This  shaking,  while  it  breaks  up  larger  masses  and  shortens  long  chains, 
does  not  to  any  great  extent  break  apart  the  shorter  chains,  diplococci, 
etc.  Each  of  these  groups  of  bacteria,  when  caught  in  the  solid  medium, 
develops  as  a  single  colony. 

(£)  It  is  impossible  to  obtain  a  medium  suited  to  the  food  require- 
.ments  of  all  species  or  races  of  bacteria  (2).  (See  foot-note.) 

It  has  been  found  by  experiment  that  a  medium  consisting  chiefly 
of  a  watery  extract  of  raw  meat,  alkaline  to  litmus  and  slightly  acid  to 
phenolphthalein,  will  furnish  the  best  food  for  the  greatest  number  (3). 

(c}  These  varying  forms  of  minute  vegetable  life  require  varying 
temperatures  for  their  best  development.  Many  forms  which  will  de- 
velop at  room  temperature  will  not  grow  at  bod}'  temperature.  Some 
require  a  very  high  temperature  for  their  best  growth. 

(d)  Some  bacteria  develop  in  an  atmosphere  free  from  oxygen, 
some  only  where  oxygen  is  present  ;  many  are  facultative  growing  under 
either  condition.  Bacteria  which  require  an  oxygen -free  atmosphere  do 
not  develop  in  plates  as  generally  prepared.  Bacteria  requiring  oxygen, 
if  deep  in  the  medium,  develop  but  slowly,  as  they  obtain  oxygen  only 
by  diffusion. 

•  (e)  Many  forms  are  slow  in  developing  into  visible  colonies,  some 
requiring  three  or  four  days.  On  the  other  hand,  in  plates  grown  for 
several  days  many  small  colonies  are  obscured  in  the  growth  of  larger 
ones  (4). 

(/)  Each  bacterium  requires  a  certain  amount  of  nourishment  for 
development  (5).  There  are  also  antagonistic  forms  which  will  not 
develop  in  close  proximity  to  each  other.  '  It  therefore  follows  that  in  a 
crowded  plate,  i.  e.,  over  two  hundred  colonies,  many  will  not  develop 
(6).  This  is  easily  proven  by  making  a  higher  dilution. 

Of)  Spreaders  and  molds,  by  their  rapid  surface  growth,  merge  with 
other  surface  colonies  and  obscure  deeper  ones. 

(#)  Samples  kept  in  the  collecting  case  at  34°  F.  for  varying  periods 
have  shown  a  tendency  to  decrease  in  the  number  of  bacteria  which  will 
develop  into  colonies  (7).  Samples  kept  in  dilution  water  for  several 
hours  have  shown  a  marked  decrease  in  the  number  of  bacteria  which 
will  develop  into  colonies  (8). 

( )n  account  of  these  reasons  strict  adherence  to  standard  procedure  is 
of  especial  importance,  since  there  are  so  many  points  where  disagree- 
ment may  result  if  uniform  technique  is  not  followed. 

NOTK. — The  reference  numbers  occurring  in  the  Committee  report  refer  to  the  bibli- 
ography accompanying  the  same,  appearing  on  puye  I5n. 


Xr:\IKRIC.\I,   DKTKRMINATIOX  OF  BACTKKIA.  143 

Since  at  best  only  approximate  results  can  be  reached  in  the  numerical 
determination  of  bacteria  in  milk,  and  since  from  the  varying  methods 
in  use  at  present  counts  from  different -workers  are  usually  incomparable, 
those  methods  which  have  given  best  results  as  a  whole  should  be  united 
ui)on  and  adopted  by  all,  that  a  bacterial  count  on  a  sample  of  milk  may 
mean  the  same  if  made  in  any  standard  laboratory. 

.CoijvKCTioN  OF  SAMPLES. 

(Quantity  of  milk  required  for  analysis.  The  minimum  quantity  of 
milk  necessary  for  making  an  ordinary  bacteriological  examination  is  ten 
cubic  centimeters.  When  making"  examinations  for  certified  milk,  if 
possible  a  pint  or  quart  bottle  should  be  taken  and  brought  to  the  labor- 
atory unopened. 

Collecting  apparatus.  In  collecting  milk  samples  for  bacteriological 
examination  it  is  essential  that  the  sample  be  taken  and  kept  in  such  a 
manner  as  to  prevent  either  any  addition  of  bacteria  from  without  or 
multiplication  of  the  bacteria  originally  present  (9>.  Bottles,  tubes, 
pipettes,  etc.,  used  in  the  collection  of  samples,  besides  being  washed, 
shall  be  sterilized  with  dry  heat  for  an  hour  at  or  about  160°  C.,  or  to  the 
charring  point  of  cotton. 

In  the  selection  of  "certified  milk  "  samples  it  is  recommended  wher- 
ever possible  that  an  unopened  bottle  be  taken,  placed  in  a  suitably  iced 
case  and  brought  at  once  to  the  laboratory. 

vSamples  of  "market  milk"  may  be  collected  as  are  water  samples, 
in  sterile,  wide-mouthed,  glass-stoppered  four-ounce  bottles  ;  the  case  in 
which  they  are  carried  being  well  iced  (10).  The  principal  difficulty 
encountered  in  this  method  is  in  transferring  the  sample  from  the  origi- 
nal container  to  the  bottle,  and  the  various  string  and  wire  devices  by 
means  of  which  the  bottle  is  immersed  in  the  original  container  are 
objectionable  both  on  account  of  the  labor  of  preparing  such  an  outfit 
and  also  on  account  of  the  coating  of  milk  left  on  the  outside  of  the 
bottle  when  the  sample  has  been  taken. 

An  apparatus  designed  for  the  use  of  thirty-two  test  tubes  as  containers 
(11.)  is  recommended  as  superior  to  one  designed  for  bottles. 

It  has  been  proven  that  with  samples  kept  properly  iced  in  this  par- 
ticular form  of  case  there  is  no  increase  of  bacterial  content  even  for 
twenty-four  hours,  but  rather  a  slight  decrease  (7),  the  counts  varying 
hardly  more  than  might  be  expected  in  duplicate  plates.  It  is  recom- 
mended, however,  that  examination  of  the  samples  be  proceeded  with  as 
quickh-  as  possible  after  the  collections  are  made. 

Identification  of  samples.  When  bottles  are  used  identification  num- 
bers should  be  etched  on  both  bottle  and  stopper.  Test  tubes  .should  be 
labeled  or  etched  (12)  and  numbered. 

A  complete  record  of  the  samples  taken,  giving  date,  time,  place, 
name  of  party  from  which  sample 'is  taken,  name  of  collector,  tempera- 


144  BACTERIOLOGICAL  EXAMINATION  OK   MILK. 

ture  of  milk,  character  of  original  container  (tank,  can,  lx>ttle),  etc., 
should  be  written  opposite  duplicate  numbers  in  a  blank  book  or  pocket 
card  catalogue,  or  this  information  ma}-  be  written  on  small  tags  and 
tied  or  wired  to  the  corresponding  test  tuBe  or  bottle. 

Temperature.  The  temperature  should  be  taken  immediately  after 
taking  the  sample  for  analysis,  while  the  milk  is  still  thoroughly  mixed. 

If  it  is  desired  to  take  the  temperature  of  "certified  milk,"  this  should 
be  done  wyhen  the  sample  is  taken,  but  from  another  bottle. 

A  floating  thermometer,  graduated  to  the  Fahrenheit  scale,  is  most 
convenient,  and  the  temperature  should  be  expressed  to  the  nearest 
degree.  It  is  necessary  to  standardize  the  thermometer  for  at  least  ten 
degrees  on  each  side  of  the  legal  temperature  limit.  A  quickly  regis- 
tering thermometer  should  be  left  at  least  one  minute  in  the  milk  and 
read  as  soon  as  removed.  A  small  piece  of  clean  absorbent  cotton  may 
be  used  to  wipe  the  adhering  milk  from  the  thermometer  that  the  scale 
may  be  easily  seen. 

Representative  samples.  The  collector  should  always  select  his  own 
sample,  and  care  should  be  taken  to  secure  a  sample  which  is  truly  rep- 
resentative of  the  milk  to  be  examined. 

One  of  several  methods  of  mixing  the  milk  may  be  used,  comparison 
having  shown  the  results  to  be  practically  the  same  (9). 

1.  Pouring  the  milk  into  a  sterile  receptacle  and  back. 

2.  Shaking  the  milk  thoroughly  with  receptacle  turned  upside  down. 
(This  may  be  done  where  the  can  or  bottle  is  tightly  stoppered  or  capped 
and  is  not  so  full  as  to  prevent  thorough  agitation. ) 

3.  In  open  tanks  in  stores  it  is  allowable  to  stir  thoroughly  with  the 
long-handled  dipper  generally  found  in  use. 

4.  Where  the  test  tube  collecting  case  is  used,    thoroughly  reliable 
results  are  secured  by  first  shaking  the  can  or  bottle  ;  and,  second,  stir- 
ring with  the  large  pipette  before  taking  the  sample,  care  being  taken  to 
close  the  upper  end  of  the  pipette  with  the  finger  so  that  no  milk  enters 
until  after  the  mixing,  or  the  pipette  may  be  emptied  after  stirring  before 
the  sample  is  taken. 

5.  For  certified  milk  samples  it  is  recommended  that,  on  arrival  at 
the  laboratory,   the  bottle  be  opened    with  aseptic   precautions  and  the 
milk  thoroughly  mixed  by  pouring  back  and  forth  between  the  original 
bottle  and  a  sterile  bottle.       Another  method  is  to  mix  as  thoroughly  as 
possible  by  agitation  for  five  minutes,  then  burn  through  the  paste-board 
stopper  with  a- hot  iron  and  remove  the  desired  amount  of  milk  with  a 
sterile  pipette  (13). 

The  interval  between  collection  and  analysis.  Generally  speaking  the 
shorter  the  time  between  the  collection  and  examination  of  milk  samples 
the  more  accurate  will  be  the  results.  For  routine  work  the  attempt 
should  be  made  to  plate  within  four  hours  of  the  time  of  collection. 

Too  much  stress  cannot  be  laid  on  keeping  the  samples  properly  iced 


NUMERICAL  DKTKRMIXATIOX   OF   HACTKRIA.  145 

during  tliis  interval.      They  should  be  kept  below  40°  F.,  but  care  should 
be  taken  that  the}'  are  not  frozen. 

DILUTIONS. 

Ordinary  potable  water,  sterili/.ed,  may  be  used  for  dilutions.  Occa- 
sionally spore  forms  are  found  in  such  water  which  resist  ordinary  auto- 
clave sterilization  ;  in  such  cases  distilled  water  may  be  used  or  the 
autoclave  pressure  increased.  With  dilution  water  in  eight-ounce  bottles 
calibrated  for  ninety-nine  cubic  centimeters  all  the  necessary  dilutions 
can  be  made. 

Short,  wide-mouthed  ' '  Blakes  ' '  or  wide-mouthed  French  square  bottles 
are  more  easily  handled  and  more  economical  of  space  than  other  forms 
of  bottles  or  flasks  ( 11  ). 

Eight-ounce  bottles  are  the  best,  as  the  required  amount  of  dilution 
water  only  about  half  fills  them,  leaving  room  for  shaking.  Ivong-fiber, 
non-absorbent  cotton  should  be  used  for  plugs.  It  is  well  to  use  care  in 
selecting  cotton  for  this  purpose  to  avoid  short-fiber  or  "dusty  cotton," 
which  gives  a  cloud  of  lint-like  particles  on  shaking.  Bottles  and  tubes 
should  be  filled  a  little  over  the  99  cc.  and  9  cc.  marks  to  allowr  for  loss 
during  sterilization  (14). 

The  dilutions  recommended  are  1-10,  1-100,  1-1,000,  1-10,000,  1-100,- 
000  and  1-1,000,000. 

For  certified  milk  the  1-10  and  1-100  dilutions  should  be  used,  while 
the  1-10,000  will  usually  be  found  best  for  market  milk. 

The  1-10  dilution  is  prepared  by  shaking  the  milk  sample  twenty-five 
times  and  then  transferring  1  cc.  of  the  milk  to  a  test  tube  containing  9 
cc.  of  sterile  wrater. 

The  1-100  dilution  is  prepared  in  the  same  way,  except  that  a  bottle 
with  99  cc.  of  sterile  water  is  substituted  for  the  test  tube. 

The  1-1,000  dilution  is  prepared  by  first  making  the  1-100  dilution, 
shaking  twenty-five  times  and  transferring  1  cc.  of  the  dilution  to  a  test 
tube  containing  9  cc.  of  sterile  water. 

It  is  recommended  that  that  dilution  be  used  which  will  produce 
about  two  hundred  colonies  to  a  plate,  ranging  from  40  to  400 ;  where  a 
1-10  dilution  exceeds  this  number  the  1-100  dilution  is  more  accurate,  etc. 
The  number  of  bacteria  present  may  if  desired  be  approximately  esti- 
mated before  dilutions  are  made  by  direct  microscopic  examination  of  a 
properly  prepared  sediment.  Otherwise  it  is  necessary  to  make  a  range 
of  dilutions,  thereafter  selecting  for  record  the  count  obtained  on  that 
plate  which  yields  between  40  and  400  colonies. 

Plating  whole  milk  is  unreliable  (15),  whatever  qualities  be  used, 
since  the  bacteria  are  not  so  well  separated  as  in  the  dilutions,  and  often, 
owTing  to  the  crowded  conditions,  only  a  portion  of  the  bacteria  present 
will  develop  into  visible  colonies  (6).  Moreover,  if  a  cubic  centimeter 
of  the  milk  is  used,  the  turbidity  of  the  jelly,  due  to  the  presence  of  the 
milk,  hides  the  colonies  present  from  the  eye. 


146  BACTERIOLOGICAL  EXAMINATION  OF  MILK. 

MEDIA. 

The  standard  medium  for  determining  the  number  of  bacteria  in  milk 
shall  for  the  present  be  agar,  made  according  to  the  recommendations  of 
the  Committee  on  Water  Analysis  (1),  except  that  the  percentage  of 
agar  shall  be  1  per  cent,  and  the  reaction  -;  1.5  (2d). 

All  variations  from  agar  media  made  as  described  shall  be  considered 
as  special  media. 

Much  work  yet  remains  to  be  done  on  media  ;  the  above  is  recom- 
mended as  giving  the  highest  and  most  uniform  counts  as  far  as  our  com- 
parative work  has  extended  and  with  but  slight  variations  is  the  medium 
in  most  common  use. 

Storage  of  media.  Media  may  be  made  up  in  quantity,  tubed  and 
stored  (preferably  in  an  ice  chamber). 

PivATixr,. 

Plating  apparatus  (11).  For  plating  it  is  best  to  have  a  single  water 
bath  in  which  to  melt  the  media  and  a  water-jackettd  water  bath  for 
keeping  it  at  the  proper  temperature  ;  a  wire  rack,  which  should  fit  both 
of  the  water  baths,  for  holding  the  media  tubes ;  a  thermometer  for 
recording  the  temperature  of  the  water  in  the  water-jacketed  bath  ;  ster- 
ile 1  cc.  pipettes ;  sterile  petri  dishes ;  and  sterile  dilution  water  in 
measured  quantities. 

For  milk  work  porous  earthenware  petri  dish  covers  (16),  are  much 
superior  to  glass  covers,  .since  they  absorb  the  excess  moisture  from  the 
agar  and  prevent  "spreading." 

It  is  quite  essential  to  the  best  results  that  the  porous  covers  should 
be  wet  as  seldom  as  possible.  In  sterilizing  them  the  process  should  be 
prolonged  over  the  time  necessary  to  kill  the  organisms  in  order  that 
the  covers  ma}-  be  thoroughly  dry. 

Extract  from  the  1908  report.  A  method  of  avoiding  the  troubles  due 
to  moisture  consists  of  inverting  the  plates,  and  putting  in  the  lid  of 
each  petri  dish,  a  strip  of  blotting  paper  on  which  there  is  a  large  drop 
of  glycerine.  Incubate  as  directed. 

As  a  result  of  these  experiments  we  feel  that  the  agar  plates  with 
glycerine,  prepared  in  the  manner  above  indicated,  are  slightly  more 
reliable  than  the  earthenware  tops. 

The  principal  objections  to  the  latter  are  : 

(1)  They  scratch  the  glassware. 

(2)  The  plate  has  to  be  uncovered  for  examination,  and 

(3)  They  are  more  liable  to  dry  out  if  kept  longer  than  36  hours. 
Straight-sided  1  cc.  pipettes  are  more  easily  handled    than  those  with 

bulbs  ;  they  may  be  made  from  ordinary  glass  tubing  about  ^  of  aw  inch 
in  diameter  and  calibrated  in  the  laboratory  (17).  They  should  be  made 
about  ten  inches  in  length. 


NUMERICAL  DETERMINATION  OF  BACTERIA..  147 

riating  technique.  The  agar  after  melting  should  be  kept  in  the 
water-jacketed  water  bath  between  40° C  and  45°C.  for  at  least  fifteen 
minutes  before  using,  to  make  sure  that  the  agar  itself  has  reached  the 
temperature  of  the  surrounding  water.  If  used  too  warm  the  heat  may 
destroy  some  of  the  bacteria  or  retard  their  growth. 

For  routine  work  in  cities  in  order  to  bring  down  the  actual  number 
of  colonies  in  a  plate  around  the  standard  of  two  hundred,  it  is  well  to 
use  a  dilution  of  1-10,000.  To  make  this  dilution  use  two  bottles  of 
sterile  water  each  containing  99  cc. 

Shake  the  milk  sample  twenty-five  times,  then  with  a  sterile  pipette 
remove  1  cc.,  put  into  the  first  dilution  water  and  rinse  the  pipette  by 
drawing  dilution  water  to  the  mark  and  expelling  ;  this  gives  a  dilution 
of  1  to  100. 

Shake  the  first  dilution  twenty-five  times,  then  with  a  fresh  sterile 
pipette  remove  1  cc.,  put  into  the  second  dilution  water,  rinsing  the 
pipette  to  the  mark  as  before  ;  this  gives  a  dilution  of  1  to  10,000.  Shake 
the  second  dilution  twenty-five  times,  then  with  a  sterile  pipette  remove 
1  cc.,  and  put  it  into  the  petri  dish,  using  care  to  raise  the  cover  only  so 
far  as  necessary  to  insert  the  end  of  the  pipette. 

Taking  a  tube  of  agar  from  the  water  bath,  wipe  the  water  from  out- 
side of  tube  with  a  piece  of  cloth,  remove  the  plug,  pass  the  mouth  of 
the  tube  through  the  flame,  and  pour  the  agar  into  the  plate,  using  the 
same  care  as  before  to  avoid  exposure  of  the  plate  contents  to  the  air. 

Carefully  and  thoroughly  mix  the  agar  and  diluted  milk  in  the  petri 
dish  by  a  rotary  motion,  avoiding  the  formation  of  air  bubbles  or  slop- 
ping the  agar,  and  after  allowing  the  agar  to  harden  for  at  least  fifteen 
minutes  at  room  temperature  place  the  dish  bottom  down  in  the  incuba- 
tor. The  practice  of  mixing  the  diluted  milk  with  the  agar  in  the  in  he, 
leaving  a  certain  portion  of  the  bacteria  unplated,  is  not  recommended 
by  the  Committee. 

Controls.  Plating  should  always  be  checked  by  controls.  A  blank 
plate  should  be  made  with  each  set  of  milk  plates  for  control  of  the  water, 
petri  dishes,  pipettes,  etc. 

For  control  on  technique  of  plating  it  is  recommended  that  for  work 
on  "market  milk,"  duplicates  be  made  each  day  on  several  plates. 

"  Certified  milk"  should  always  be  plated  in  duplicate,  and  where  pos- 
sible it  is  well  to  have  one  man's  work  occasionally  checked  by  another. 

Unless  duplicate  plates  show  as  a  rule  approximately  the  same  count, 
the  worker  should  see  if  there  is  error  in  his  technique. 

Racks  are  very  useful  for  stacking  the  plates  and  to  prevent  breakage. 

Plating  should  be  done  always  in  a  place  free  from  dust  or  currents 
of  air. 

In  order  that  the  colonies  may  have  sufficient  food  for  proper  develop- 
ment, 10  cc.  of  agar  shall  be  used  for  each  plate.  In  plating  a  large 
number  of  samples  at  one  time  the  dilution  and  transfer  of  diluted  milk 


148  BACTERIOLOGICAL  EXAMINATION  OF  MILK. 

to  the   plates  may   be  done    for   four  or  eight  samples,    then    the   agar 
poured,  one  tube  to  each  plate,  then  another  eight  samples  diluted,  etc. 

INCUBATION. 

Methods.  Concerning  incubation  two  methods  are  at  present  in  use. 
Three-fifths  of  the  laboratory  workers  consulted  recommended  incuba- 
tion at  37°  C.  for  twenty-four  hours  with  saturated  atmosphere,  the 
remaining  two- fifths  allowed  varying  lengths  of  time  at  different  degrees 
of  room  temperature  and  at  whatever  degree  of  humidity  happened  to 
obtain. 

When  considering  these  two  methods  many  ad  vantages. of  the  method 
of  incubation  at  37°  C.  are  evident,  including  the  ease  of  maintaining 
this  temperature  in  any  laboratory,  the  evident  uniformity  of  counts  so 
obtained  in  different  places  as  compared  with  those  obtained  by  the 
varying  methods  of  technique,  as  to  temperature,  and  incubation  period, 
where  room  temperature  is  employed,  and  the  quickness  with  which 
results  are  obtained,  doing  away  with  large  accumulations  of  uncounted 
plates. 

Forty-eight  hour  plates  grown  at  37°  C.  give  a  slightly  higher  count 
(11),  not  enough  higher  to  materially  change  the  report,  while  the  loss 
by  "spreaders"  is  increased  and  the  count  delayed. 

To  secure  saturation  of  the  atmosphere  the  incubator  should  be  made 
with  a  shallow  depression  over  the  whole  bottom  surface,  which  may  be 
kept  filled  with  water,  or  in  default  of  this  a  large  shallow  pan  of  water 
may  be  kept  on  one  of  the  lower  shelves. 

Much  work  will  be  done  on  comparison  of  37°  C.  and  ' '  room  temper- 
ature "  during  the  coming  year. 

Extract  from  1908  report.  Summarizing  up  the  work  on  incubation, 
we  ma}-  say  that  the  weight  of  evidence  is  against  24  hours  incubation  at 
37°  C.  and  two  day  incubation  at  or  around  21°  C.,  the  number  of  col- 
onies obtained  being  too  small  for  a  fair  idea  of  the  number  of  bacteria 
in  the  sample. 

Bight  day  and  ten  day  incubations  at  21°  C.,  while  giving  a  slightly 
higher  average  count,  have  disadvantages,  such  as  delay  in  reports, 
accumulation  of  plates  and  drying  out  of  media,  which  render  them 
undesirable  for  routine  work. 

The  lines  of  highest  efficiency  on  a  working  basis  would  seem  to  rest 
on  a  48  hour  incubation  at  37°  C.  and  a  five  day  incubation  at  21°  C. 

It  would  seem  advisable  to  recognize  as  standard  both  of  these 
methods  of  incubation  (it  being  understood  that  carefully  regulated 
incubators  should  be  used). 

Board  of  Health  regulations  governing  the  number  of  bacteria  allow- 
able in  milk,  should  state  the  method  to  be  used  in  examination  and  in 
all  reports,  papers,  etc. ,  on  the  bacterial  count  of  milk  this  factor  should 
be  explicitly  stated. 


NUMERICAL  DETERMINATION  OF  BACTERIA. 


149 


COUNTING. 

Expression  oj  results.  Since  minor  differences  in  milk  counts  are 
within  the  working  error  of  the  methods  and  are  of  no  significance  in 
practice,  the  following  scale  has  been  adopted  for  recording  results  of 
market  milk  examinations  : 

Counts  below  100,000  are  distinguished  by  ten  thousands. 

Counts  between  100,000  and  500,000  are  distinguished  by  fifty  thou- 
sands. 

Counts  between  500,000  aud  1,000,000  are  distinguished  by  hundred 
thousands. 

Counts  between  1,000,000  and  2,000,000  are  distinguished  by  two  hun- 
dred thousands. 

Counts  between  2, 000, 000  and  5,000,000  are  distinguished  by  five  hun- 
dred thousands.  . 

Counts  above  5,000,000  are  distinguished  by  millions. 

Therefore  only  the  following  figures  are  used  in  reporting  : 

Below     10,000         Above 
Above     10,000 

20,000 

30,000 

40,000 

50,000 

60,000 

70,000 

80,000 

90,000 
"  100,000 
"  150,000 
"  200,000 

Counts  on  ' '  certified  "  or  "  inspected  ' '  milk  shall  be  expressed  as 
closely  as  the  dilution  factor  will  allow. 

The  whole  number  of  colonies  on  the  plate  shall  be  counted,  the  prac- 
tice of  counting  a  fractional  part  being  resorted  to  only  in  case  of  neces- 
sity, such  as  partial  spreading. 

Various  counting  devices  have  been  recommended  by  different  work- 
ers. The  more  simple  ones,  where  the  whole  plate  can  be  seen  at  once, 
are  more  desirable  on  account  of  there  being  less  likelihood  of  recount- 
ing colonies.  Colonies  too  small  to  be  seen  with  the  naked  eye  or  with 
slight  magnification  shall  not  be  considered  in  the  count. 


250,000 

Above   1,400,000 

300,000 

"       1,600,000 

350,000 

"       1,800,000 

400,000 

"       2,000,000 

450,000 

11       2,500,000 

500,000 

"       3,000,000 

600,000 

11       3,500,000 

700,000 

"       4,000,000 

800,000 

"       4,500,000 

900,000 

"       5,000,000 

1,000,000 

6,000,000 

1,200,000 

etc..  by  millions 

150  BACTERIOLOGICAL  EXAMINATION  OF  MILK. 

BIBLIOGRAPHY  OF  COMMITTEE  REPORT. 

1.  Transactions  A.  P.  H.  A.,  Vol.  XXX,  Part  II. 

2.  Comparison  of  Media. 

a.  Heinemann,  Appendix  A.* 

b.  Prescott,  Appendix  B.:;: 

c.  Prescott,   Technology  Quarterly,  Vol.  XVIII,  No.  3,  page  252. 

d.  Report  Boston  Board  of  Health,  1906,  page  74. 

3.  Fuller  and  Copeland,  Report  Massachusetts  State  Board  of  Health, 
1906,  page  585.     Muir  and  Ritchie,  1903,  page  37. 

4.  Slack,  Appendix  C.* 

5.  Hill  and  Rllms,  Report  of  Brooklyn  Water  Supply,  1897. 

6.  Hill,  the  Mathematics  of  the  Bacterial  Plate  Count ;  Paper  read 
before  Laboratory  Section  A.  P.  H.  A.,  Sept.  30,  1907. 

7.  Slack,  Appendix  D.* 

8.  Slack,  Appendix   E.* 

9.  Report  Boston  Board  of  Health,  1906,  page  76. 

10.  Stokes,  Appendix  F.* 

11.  Hill  and  Slack,  American  Journal  of  Public  Hygiene,   November, 
1904,  page  237. 

12.  Gorham,  Laboratory  Course  in  Bacteriology,  page  54. 

13.  Method  used  by    H.  W.   Hill,   Minnesota  State  Board   of   Health 
Laboratory. 

14.  Heinemann,  Appendix  G.* 

15.  Campbell,  Appendix  H.* 

16.  Hill,  Journal  of  Medical  Research,  Vol.  XIII,  No.  1  (New  Series, 
Vol.  VIII,  No.  1),  pages  93-96,  December,  1904. 

17.  Gage,  Appendix  I.* 


Significance  of  results.  In  the  interpretation  of  the  results 
of  the  numerical  determination  of  bacteria  in  milk,  it  must 
be  constantly 'borne  in  mind  that  the  results  indicate  only  con- 
ditions at  the  moment  the  sample  was  taken.  We  are  not 
dealing  with  the  quantitative  estimate  of  a  milk  constituent 
like  fat,  which  is  present  in  the  same  proportion  in  .a  given 
sample  a't  all  times.  It  must  be  remembered  that  a  bacterial 
count  is  a  measure  of  the  progress  of  multiplication  of  a  com- 
plex mixture  of  micro-organisms,  controlled  by  an  equally 
complex  series  of  factors.  The  results  at  any  given  time 
depend  in  part  upon  initial  numbers,  species,  characteristics 
of  the  milk,  its  age,  the  temperature  at  which  it  has  been  kept, 

*  Reference  to  Appendix   of  Committee  report,  to  be  found  in  the  American  Journal 
of  Public  Hyiriene,  N.  S.  Vol.  Ill,  1901,  No.  5,  pp.  354  to  364. 


MICROSCOPIC  ESTIMATE  OF  BACTERIA.  151 

and  the  method  of  making:  the  determination.  Wrong  con- 
clusions will  be  reached,  if  emphasis  is  laid  upon  mere  num- 
bers without  a  consideration  of  the  other  factors. 

A  numerical  determination  taken  by  itself  without  full 
consideration  of  all  the  factors  involved  has  no  value.  Per- 
sons not  familiar  with  the  circumstances  are  apt  to  attempt 
to  make  comparisons  when  such  are  inadmissible.  The  results 
of  the  work  of  two  laboratories  cannot  be  compared,  unless 
there  has  been  uniformity  in  every  detail  that  would  affect 
results.  Every  bacteriologist  doing  much  milk  work  has  had 
embarrassing  experiences  along  this  line.  The  man  who  has 
had  the  longest  experience  with  numerical  determinations  of 
bacteria  in  milk  in  connection  with  milk  commission  work 
believes  that  no  good  end  is  served  by  stating  results  publicly 
in  numerical  terms,  and  acts  in  accordance  therewith.  In  any 
event,  the  publication  of  numerical  results  should  be  restricted 
to  a  small  circle  of  persons  wrho  appreciate  their  significance. 

The  bacterial  count  is  undoubtedly  the  instrument  by  which 
the  effectiveness  of  good  dairy  methods  is  measured,  and  has 
been  a  prominent  factor  in  the  development  of  those  methods. 
It  reveals  facts  regarding  the  operation  of  high  grade  dairies 
that  no  inspection  could  disclose.  A  count  of  certified  milk 
is  better  evidence  of  the  observance  of  certain  features  of 
cleanliness  in  handling  the  milk  than  a  visit  to  the  dairy. 

The  value  of  the  bacterial  count  in  locating  contamination 
is  recognized  by  careful  dairymen.  Some  large  distributing 
firms  use  the  method  to  good  advantage  in  controlling  the 
producing  dairies.  Postal  card  reports  sent  from  time  to  time 
convince  the  dairyman  that  his  product  is  under  scrutiny  and 
stimulate  him  to  greater  efforts. 

Microscopic  estimate  of  bacteria.  Slack  has  observed  that,  in 
connection  with  his  method  for  the  study  of  milk  sediments, 
the  number  of  bacteria  may  also  be  roughly  estimated.  By  a 
long  series  of  comparative  tests,  it  has  been  found  possible  to 
tell  from  the  number  of  bacteria  in  the  smear  whether  or  not 
plate  cultures  would  show  above  or  below  500,000  colonies  per 
cc.  An  error  of  less  than  \(/<  was  made  in  this  regard.  Slack 
uses  the  test  to  eliminate  those  samples  of  milk  that  are  well 


152  BACTERIOLOGICAL  EXAMINATION  OF  MILK. 

within  the  limit,  and  thus  saves  the  trouble  of  plating  them. 
The  committee   of  the  A.  P.  H.  A.  in   its   1908   report   (4) 
makes  the  following  comment  : 

"  Several  laboratories  are  now  making  this  examination  as  a  routine 
procedure.  One  \vorker  (Conn),  who  has  done  considerable  experimen- 
tation along  this  line  during  the  past  year  sums  up  his  results  in  attempts 
to  actually  approximate  plate  counts  as  follows  : 

1  The  method  seems  to  be  fairly  satisfactory  for  milk,  the  bacterial 
content  of  which  is  not  too  low  or  too  high.  When  the  numbers  are  down 
below  ten  thousand  the  method  seems  to  be  quite  inaccurate,  and  when 
the  numbers  run  up  into  the  millions  I  find  also  the  numbers  are  not 
very  reliable.  Within  the  limits  of  from  thirty  thousand  to  three  hun- 
dred thousand,  however,  the  method  seems  to  be  fairly  good.  I  have, 
however,  had  the  experience  of  occasionally  finding  samples  of  milk  ' 
which,  when  tested  by  direct  microscopic  methods,  gave  results  very 
different  from  those  by  the  plate  method.  My  general  feeling  is  that  a 
direct  microscopic  method  might  give  an  idea  as  to  whether  the  sample 
is  very  good  or  very  bad,  but  would  not  replace  the  plate  method  of 
examination  in  determining  actual  numbers  and  would  be  of  no  use  for 
the  examination  of  samples  of  milk  whose  number  of  bacteria  is  quite  low.' 

"Another  (Campbell),  who  has  done  much  work  with  this  method, 
finds  it  chiefly  useful  as  a  preliminary  test,  not.  plating  samples  which 
are  shown  by  the  microscope  to  contain  less  bacteria  than  the  city  regu- 
lation permits,  in  those  samples  which  are  plated  it  serves  as  a  guide  for 
the  proper  dilutions.  He  finds  it  possible  with  this  examination  to  cor- 
•  rectly  state  in  nearly  every  instance  \vhen  a  milk  contains  less  than  50,- 
000  bacteria  to  a  cubic  centimeter,  or  when  it  contains  over  a  million  bac- 
teria to  the  cc.  On  actual  estimates  within  50,000  of  the  plate  count  his 
average  is  66%  correct  on  counts  between  50,000  and  500,000  and  50% 
correct  on  counts  between  500,000  and  1,000,000." 

The  subject  of  the  microscopic  examination  of  milk  for  leu- 
cocytes and  streptococci  is  discussed  in  Chap.  VII. 

Tests  for  B.  coli«  Methods  for  the  examination  of  milk  for 
B.  coli  are  in  the  process  of  evolution.  The  question  of  the 
accuracy  and  significance  of  some  of  these  tests  has  received 
some  attention  by  the  committee  of  the  A.  P.  H.  A.  in  its  1908 
report.  The  methods  have  hardly  been  tested  out  sufficiently 
to  warrant  recommendation  for  general  use. 

Examinations  for  typhoid  fever  and  diphtheria  bacilli.  In 
connection  with  the  investigation  of  milk-borne  epidemics  of 
typhoid  fever  and  diphtheria,  the  desire  is  very  frequently 


~    TUBERCLE  BACILIJ.  153 

expressed  for  an  examination  of  the  milk  with  respect  to  the 
presence  or  absence  of  the  germs  of  these  diseases.  The  tech- 
nical difficulties  at  present  surrounding  such  work  are  too 
great  to  render  it  worth  undertaking  as  a  matter  of  routine. 
Then  too  it  is  very  likely  the  germs  may  not  be  present  at  the- 
time  milk  is  under  suspicion,  which  may  be  long  after  the  pol- 
lution of  the  milk  occurred.  The  presence  of  diphtheria  bacilli 
in  milk  has  been  demonstrated  by  the  inoculation  of  guinea- 
pigs  with  centrifugal  sediment  and  the  production  of  diph- 
theria. The  relation  of  milk  to  these  diseases  as  demonstrated 
by  other  means  is  discussed  in  Chap.  III. 

Tubercle  bacilli.  The  examination  of  milk  for  tubercle 
bacilli  is  not  recommended  as  a  profitable  line  for  routine  work. 
Owing  to  the  fact  that  tubercle  bacilli  appear  in  milk  inter- 
mittently, a  negative  result  is  of  no  significance  in  showing 
the  usual  quality  of  the  milk  in  this  regard.  Nevertheless, 
occasions  arise  when  the  interest  in  the  result  warrants  the 
trouble  taken  to  secure  the  information  as  to  the  presence  of 
the  tubercle  bacilli. 

The  work  described  below  calls  for  the  use  of  a  large  centrif- 
ugal machine  instead  of  the  ordinary  machine  used  in  urine 
analysis,  but  the  latter  may  be  employed  with  the  disadvantage 
of  using  the  smaller  amount  of  milk.  The  technic-  varies 
somewhat  with  different  wrorkers,  but  that  of  Anderson  (l) 
is  given  here  and  is  also  recommended  by  the  A.  P.  H.  A. 
committee. 

To  50  cc.  of  well-mixed  sample  in  a  sterile  centrifuge  flask,, 
add  100  cc.  of  sterile  distilled  water.  Centrifugalize  at  2,000 
revolutions  for  one  hour.  Five  cc.  of  the  sediment  is  inocu- 
lated into  each  of  at  least  two  guinea-pigs  subcutaneously  in 
the  abdomen,  using  a  different  syringe  for  each  pig.  An 
equal  number  of  control  pigs  are  kept  with  those  inoculated, 
as  a  control  on  health  of  stock,  environment,  etc. 

Examine  for  enlarged  glands  after  four  weeks  and  separate 
those  showing  evidence  of  tuberculosis.  Pigs  are  apt  to  die 
early  from  acute  infections  resulting  from  bacteria  in  the  milk 
other  than  tubercle  bacilli.  Those  alive  at  two  months  are 
given  2  cc.  of  crude  tuberculin,  which  kills  badly  tubercular 


154  BACTERIOLOGICAL   EXAMINATION  OF  MILK. 

pigs  and  sickens  those  with  slight  lesions.  Others,  presumably 
non-tubercular,  are  chloroformed.  At  autopsy,  all  organs 
showing  deviations  from  the  normal  are  examined  for  tuber- 
culosis by  smears,  cultures  and  sections.*  Care  must  be  taken 
to  differentiate  tuberculosis  from  the  lesions  of  Bacillus  pseudo 
tuberculosis.  This  organism  causes  peritonitis  with  adhesions 
and  nodules  in  organs  like  the  liver  or  spleen,  which  show 
a  tendency  to  central  necrosis.  In  section  these  nodules  are 
seen  to  consist  of  lymphoid  elements,  very  few  epithelioid  and 
multinuclear  cells.  The  giant  cells  typical  of  tuberculosis  do 
not  occur.  Cultures  grow  more  rapidly  than  those  of  //. 
tuberculosis. 

The  older  method  of  direct  microscopic  examination  of  milk 
sediments  for  tubercle  bacilli  is  quite  inadmissible,  and  all  con- 
clusions based  upon  it  have  to  be  discarded.  Other  organisms 
having  the  staining  peculiarities  of  B.  tuberculosis  (acid-fast) 
are  frequently  found  in  dairy  products.  Johne's  disease, 
affecting  the  intestines  of  cattle,  is  caused  by  an  organism 
similar  in  morphology  to  B '.  tuberculosis. 

Determination  of  streptococci.  Streptococci  may  be  recog- 
nized on  the  plates  made  in  connection  with  the  standard 
method  for  numerical  determination.  The  colony  is  small, 
consisting  of  a  slightly  elevated  center  surrounded  by  a  thin 
spreading  border.  Their  significance  in  a  quantitative  sense  is 
discussed  in  Chap.  VII. 

Qualitative  determinations.  The  examination  of  milk  by 
methods  permitting  the  determination  of  the  percentage  of 
various  groups  of  organisms  has  been  quite  extensively  used 
in  the  study  of  dairy  problems,  and  has  yielded  valuable 
information  (2).  Certain  characteristics  of  growth  on  plates, 
such  as  formation  of  acid,  character  of  colony,  and  liquefaction 
of  gelatin,  have  been  made  the  basis  for  the  identification  of 
groups  of  organisms  for  the'  study  of  their  growth  under  var- 
ious conditions.  The  relative  proportion  in  which  certain 


*  Dead  tubercle  bacilli,  killed  for  instance  «by  pasteurization,  may  lead 
to  the  formation  of  small  tubercles,  with  no  tendency  to  further  multi- 
plication. Some  workers  consider  it  well  to  inoculate  a  second  pig  from 
these  lesions,  to  settle  doubt  as  to  their  nature. 


REFERENCES.  155 

groups  of  organisms  are  present  in  milk  is  of  importance.  If 
is  doubtful,  however,  if  the  necessity  for  this  information  would 
warrant  the  use  of  the  method  in  the  ordinary  control  work 
in  connection  with  municipal  milk  supplies.  Qualitative 
examinations  are  of  decided  advantage  in  the  examination  of 
pustL'iiri/.ed  milk. 


REFERENCES. 

NOTK. — The  reference  numbers  in  parentheses  occurring  in  the  A.  P. 
H.  A.  report  on  pages  141  to  149  refer  to  the  bibliography  accompanying 
that  report  on  page  150. 

1.  ANDERSON.     The  frequency  of  tubercle  bacilli  in  the  market  milk 
of  Washington,  1).  C.     Bui.  No.  41,  Hyg.  Lab.,  U.  S.  Pub.  Health  and 
Mar.  Hasp.  Serv.,  Washington,  D.  C.,  1908,  p.  163. 

2.  CONN  and  ESTKN.     Qualitative  analysis  of  bacteria  in  market  milk. 
Fifteenth  Ann.  Kept.  Storrs  Agr.  Exp.  Sta.,  Storrs,  Conn.,  1903,  p.  63. 

3.  Preliminary  Statement  by  the  Committee  on  Standard  Methods  of 
Bacterial  Milk  Analysis  to  the  Laboratory  Section  of  the  American  Pub- 
lic Health  Association.     Amer.  Jour.  Pub.  Hyg.,  Vol.  XVII,  1907,  No. 
4,  N.  S.  Vol.  Ill,  No.  5,  p.  331. 

4.  Manuscript  report  of  the  same  committee  for  1908. 


CHAPTER  IX. 


CERTIFIED  MILK. 


Milk  commissions.  The  medical  milk  commission  move- 
ment is  the  outgrowth  of  the  efforts  of  one  physician  to  secure 
clean  milk.  Dr.  Henry  L.  Coit  of  Newark,  N.  J.,  recognized 
the  inadequacy  of  state  and  municipal  methods  of  dealing  with 
the  milk  problem.  He  and  his  associates,  in  1893,  organized 
a  professional  organization  known  as  the  Medical  Milk  Com- 
mission of  Essex  County,  New  Jersey.  They  drew  up  regu- 
lations covering  the  methods  of  producing  clean  milk,  quality 
of  the  product,  etc.  One  dairyman,  Mr.  Stephen  Francisco, 
agreed  to  conform  to  the  regulations  ;  in  default  of  which  he 
was  to  forfeit  the  support  of  the  commission  in  guaranteeing 
his  product  to  the  profession. 

The  object  and  scope  of  the  work  of  the  commission  were 
defined  as  follows  (8)  : 

"  The  objects  of  this  commission  are  to  establish  correct  clinical  stand- 
ards of  purity  for  cows'  milk  ;  to  become  responsible  for  a  periodical 
inspection  of  the  dairies  under  its  patronage  ;  provide  for  chemical  and 
bacteriological  examinations  of  the  product,  and  the  frequent  scrutiny  of 
the  stock  by  competent  veterinarians ;  to  promote  only  professional  and 
public  interests. 

' '  The  following  are  three  general  requirements  or  standards  for  the 
milk:  (1)  An  absence  of  large  numbers  of  micro-organisms,  and  the 
entire  freedom  of  the  milk  from  pathogenic  varieties  ;  (2)  unvarying 
resistance  to  early  fermentative  changes  in  the  milk,  so  that  it  may  be 
kept  under  ordinary  conditions  without  extraordinary  care;  (3)  a  con- 
stant nutritive  value  of  known  chemical  composition,  and  a  uniform 
relation  between  the  percentage  of  fats,  proteids,  and  carbohydrates. " 

Dr.  Coit  suggested  the  use  of  the  phrase  "  certified  milk  " 
to  designate  the  product  turned  out  under  the  approval  of  the 
commission.  Mr.  Francisco,  in  order  to  protect  the  word 

certified  ' '  from  illegitimate  u&e  by  trade  competitors,  regis- 


:\III,K   COMMISSIONS.  157 

tered  it  in  the  Patent  Office.  The  original  certified  dairy  has 
prospered  and  to-day  is  one  of  the  largest  sanitary  dairies  in 
the  country.  The  idea  of  milk  certification  spread  slowly  at 
first,  but  now  about  forty  milk  commissions  are  scattered  over 
the  country  (1,  2,  7,  8,  12). 

Association  of  milk  commissions.  For  purposes  of  mutual 
benefit,  the  various  commissions  have  formed  an  association 
under  the  name  of  The  American  Association  of  Medical  Milk 
Commissions.  The  original  purposes  of  the  association  are 
best  defined  by  Article  II  of  its  constitution  (l)  : 

' '  The  purpose  of  this  Association  shall  be  to  federate  and  bring  into 
one  compact  association  the  Medical  Milk  Commissions  of  the  United 
States ;  to  exchange  views  and  to  adopt  uniform  methods  of  procedure 
in  the  work  of  the  Medical  Milk  Commission  ;  to  fix  chemical  and  bac- 
teriologic  standards  ;  to  determine  the  scope  of  medical  and  veterinary 
inspections,  and  to  foster  and  encourage  the  establishment  of  Medical 
Milk  Commissions  in  other  cities." 

During  the  two  years  of  the  existence  of  the  association,  it 
has  abundantly  fulfilled  expectations. 

Source  of  authority .  A  milk  commission  should  derive  its 
authority  from  a  regularly  constituted  medical  society  by  whom 
it  is  appointed  and  to  whom  it  is  responsible.  The  majority 
of  the  membership  should  be  physicians,  and  the  commission 
should  be  a  strictly  medical  organization  with  professional 
objects  for  the  public  good.  It  is  quite  a  general  practice  to 
appoint  a  minority  of  lay  members  on  commissions  in  order  to 
afford  representation  for  civic  bodies  prominently  identified 
with  the  clean  milk  movement.  Exceptions  as  to  the  appoint- 
ing body  have  occurred  in  the  case  of  milk  commissions  ema- 
nating from  civic  bodies.  For  instance,  the  pioneer  milk  com- 
mission in  California  was  established  by  a  woman's  club.  It  is 
well,  however,  to  adhere  to  a  county  medical  society  as  a 
source  of  authority  in  order  to  preserve  a  sharp  distinction 
between  the  legitimate  and  the  illegitimate. 

Field  of  milk  commission  activities.  A  milk  commission  is 
not  designed  necessarily  to  invade  the  field  of  ordinary  muni- 
cipal milk  inspection,  although  some  schemes  for  such  milk 
inspection  recognize  milk  commission  work.  The  commission 


158  CERTIFIED  MILK. 

sets  the  necessary  high  standard  for  the  production  of  irre- 
proachable milk  and  agrees  to  certify  the  milk  of  as  many 
dairymen  as  desire  to  follow  its  rules.  Only  in  the  larger 
cities  should  a  commission  expect  to  enlist  a  number  of  dairy- 
men. Many  commissions  have  only  one  dairyman,  although 
it  is  rather  embarassing  to  recommend  the  milk  of  but  one 
dealer. 

In  many  cases,  a  milk  commission  cannot  demand  that  a 
dairyman  shall  sell  only  certified  milk.  The  consumers  of 
this  grade  of  milk  are  few  and  widely  scattered.  Under  such 
conditions,  the  expense  of  delivery  of  certified  milk  alone 
would  be  prohibitive.  A  commission  can  hardly  concern 
itself  with  other  business  relations  of  the  dealers  further  than 
to  refuse  certification  to  a  dealer  known  to  sell  adulterated  milk. 

The  milk  commission  reports  its  findings  to  the  appointing 
body,  whence  announcement  of  its  conclusions  is  made  to  the 
profession.  Announcement  is  best  made  by  means  of  a  postal 
card  mailed  from  month  to  month. 

Agreement  with  dairymen.  The  first  commission  entered 
into  an  elaborate  contract  with  the  dairyman,  in  which  every 
detail  was  carefully  defined.  In  other  cases,  it  has  been  found 
sufficient  to  furnish  the  dairyman  a  list  of  the  requirements  of 
the  commission  with  the  information  that  habitual  non-com- 
pliance will  result  in  the  withdrawal  of  certification.  The 
various  commissions  do  not  have  uniform  requirements,  but 
this  may  come  in  time.  The  purpose  to  be  attained  seems  to 
be  a  definition  of  minimum  requirements,  in  order  not  to  deter 
the  various  commissions  from  frying  improvements. 

Sanitary  requirements  for  dairymen.  § These  vary  slightly 
with  different  commissions.  The  following  ones,  drawn  up 
by  Professor  R.  A.  Pearson,  an  acknowledged  expert  on  the 
matter,  \vere  adopted  at  the  1907  meeting  of  the  American 
Association  of  Medical  Milk  Commissions,  and  may  well  be 
followed  : 

LOCATION  AND  CHARACTER  OF  LANDS. 

"Certified"  milk  shall  be  produced  only  on  gxxxl  farming  land, 
which,  together  with  all  equipment  and  methods,  is  approved  by  the 
Commission. 


AC.KKKMKXT  WITH    DAIRYMEN.  159 

Pastures  or  paddocks  to  which  cows  have-  access  shall  he  :  (1)  Free 
from  marsh  or  stagnant  pool  ;  (2)  Crossed  by  no  stream  which  might 
easily  become  dangerously  contaminated  ;  (3)  At  sufficient  distance  from 
offensive  conditions  to  suffer  no  bad  effect  from  them. 

I  VOCATION,  CONSTRUCTION,   LIGHTING,  AND  VENTILATION  OF  STABLES 
AND  OTHER  BUILDINGS. 

Buildings  in  which  "certified"  milk  is  produced  or  handled  shall  be 
located  where  good  drainage  can  be  secured  and  at  sufficient  distance 
from  other  buildings,  dusty  roads,  cultivated  and  dusty  fields  and  other 
possible  .sources  of  contamination,  to  avoid  excessive  dirt,  dust,  or  odors 
from  such 'places. 

The  stables  shall  be  constructed  so  as  to  favor  the  comfort  of  the  cows 
and  the  efficiency  of  labor.  The  floor  shall  be  of  cement  or  an  equally 
durable  and  non-absorbent  material,  and  sloped  to  provide  drainage. 
Stall  floors  may  be  constructed  of  sound  plank  well  laid  on  cement. 

The  inside  surface  of  the  walls  and  all  interior  construction  shall  be 
smooth,  with  tight  joints,  and  capable  of  shedding  water.  The  ceiling 
shall  be  of  smooth  material  and  dust  tight.  All  horizontal  and  slanting 
surfaces  which  might  harbor  dust  shall  be  avoided  as  far  as  possible. 

The  stable  shall  be  as  well  lighted  as  the  average  house,  and  shall 
have  an  average  of  at  least  four  square  feet  of  window  glass  for  each 
animal,  with  as  much  sunlight  as  possible,  and  the  light  evenly  dis- 
tributed. 

The  ventilation  shall  be  so  efficient  that  one  will  not  notice  a  stale, 
disagreeable,  or  strong  odor  on  entering  the  building. 

DRAINAGE. 

Drainage  from  buildings  shall  be  carried  under  ground  to  a  point  at 
least  one  hundred  feet  from  any  building  used  for  producing  or  hand- 
ling milk,  and  so  far  away  that  odors  from  the  drain  openings  can  not 
find  entrance  to  the  buildings. 

WATER  SUPPLY. 

There  shall  be  an  abundance  of  pure  water  from  an  approved  city  or 
town  supply,  or  from  a  deep  well  or  deep  spring,   thoroughly  protected 
against  the  entrance  of  surface  water  and  located  not  less  than  one  hun- 
•dred  feet  from  stable,  barnyard,  privy,  or  other  possible  sources  of  con- 
tamination. 

>No  other  water  except  that  from  approved  reservoirs  or  filters  shall  be 
used  for  cooling  milk,  cleaning  utensils,  or  otherwise  in  the  dairy  house. 
The  cows  may  be  permitted  to  drink  from  a  running  stream  of  clear 
water. 

Examination  of  water.  The  water  shall  be  examined  by  the  bacteri- 
ologist and  chemist  at  least  once  each  winter  and  once  each  summer, 


160  CKKTIFII'.l)   MII.K. 

and    ma\     be    rejected     wheiievrr    tin-   purity   is   suspected.      Samples  of 
water  tor  analysis  shall  IK-  furnished  as  ofu-n  as  requested. 

R  1-:.M(  )\  AI,   (>!•    \\'ASTK    FUOM    STA1?I,K. 

All  waste  shall  be  removed  and  the  stable  thoroughly  cleaned 
throughout  at  K-ast  once  daily.  When  cows  an-  kept  in  the  stable  con- 
tinuously, the  manure  shall  IK-  re-moved  from  the  stalls  at  least  twuv 
daily. 

Sl'KROI   XniNV.S  ()!•'    Hril.DINC.S. 

Surroundings  of  all  buildings  shall  be  kept  clean  and  in  good  order. 
The  accumulation  of  dirt,  rubbish,  manure,  or  decayed  matter  shall  not 
be  permitted.  The  stable  yard  shall  be  well  drained. 

ST<  >c  K  . 

The-  herd  shall  include  no  animal  that  is  known  to  be  diseased  or  that 
seems  to  show  evidence  of  acute,  chronic,  local,  or  other  disease,  unless 
permitted  by  the  veterinarian. 

'/i'.sV  fvr  tuht'irnlosis.  Tuberculin  shall  be  used  in  examination  for 
tuberculosis  whenever  required  by  the  rules  governing  veterinary 
inspection. 

.•Idditions  to  herd.  Animals  proposed  to  be  added  to  the  herd  shall 
be  kept  in  a  separate  quarantine  building,  at  least  two  hundred  feet 
from  the  stable,  and  their  milk  shall  not  be  used  until  approved  by  the 
veterinarian,  after  a  physical  examination  and  tuberculin  test. 

Exclusion  from  herd.  Any  animal  showing  evidence  of  general  ill- 
health  and  any  that  is  off-feed  shall  be  at  once  removed  from  the  stable 
and  its  milk  withheld. 

So  far  as  possible,  the  cows  shall  be  grouped  or  milked  in  groups,  so 
that  the  milk  collected  in  any  short  period  shall  show  about  the  same 
composition  as  the  average  for  the  herd. 

Housing.  The  cows  shall  be  kept  in  comfortable  and  healthful  quar- 
ters and  not  unnecessarily  exposed  to  inclement  weather. 

Foods.  All  food  stuffs  shall  be  kept  in  an  apartment  separate  from 
the  cows  and  used  only  after  milking,  and  shall  not  be  brought  into  the 
stable  except  just  before  being  fed. 

•Only  those  feeds  shall  be  used  which  consist  of  fresh,  palatable,  or 
nutritious  materials,  such  as  are  known  will  not  injure  the  health  of  the 
cows  or  unfavorably  affect  the  taste  or  character  of  the  milk. 

A  well-balanced  ration  shall  be  used,  and  changes  of  feed  shall  he- 
made  slowly. 

ll'afcr.     Cows  shall  be  given  fresh  water  at  least  twice  daily. 

Calving — Exclusion  from  the  herd.  Cows  shall  be  removed  from  tin- 
stable  in  which  the  herd  is  kept  at  least  twenty-one  days  before  due  to 
calve,  and  not  returned  until  seven  days  after  calving. 


AC.KKKMKXT    WITH    DAIK  YMKN.  161 

/;"  rcvv /\r.      Cows  shall  be-  permitted  to  c-xercist/. 

They  shall  be  cleaned,  milked,  and  fed  regularlv,  and  always  treated 
kindly. 

Long  hair  on  the  udder  and  surrounding  parts  shall  be  clipped. 

PREPARATION   OF  THF,  Co\V   FOR  MlLKINC,. 

Grooming',     At  least  half  an  hour  before  milking,  the  cows  shall  be 

thoroughly  cleaned,  and  compelled  to  remain  standing  until  milked. 

I'^nial  cleansing-.  Not  more  than  ten  minutes  before  each  milking, 
the  udders  and  surrounding  parts  shall  be  thoroughly  cleaned  by  the 
use  of  moist  clean  cloths. 

THE  COLLECTION  OF  THK  MILK  ;    HOURS  OF  MILKING;    METHODS  OF 
MILKING;  THK  USE  OF  THE  MILKING  MACHINE. 

Fore-milk.  The  first  three  or  four  streams  from  each  teat  shall  be 
drawn  into  a  separate  vessel  and  discarded. 

Milking  shall  be  done  in  a  quiet,  clean,  and  thorough  manner,  and  at 
regular  hours  ;  as  nearly  as  possible,  at  twelve-hour  intervals. 

No  person  not  employed  in  the  stable  shall  be  allowed  there  during 
milking. 

The  milking  machine  may  be  used  subject  to  the  approval  of  the  vet- 
erinarian and  bacteriologist. 

Milk  to  be  discarded.  If  the  milk  appears  bloody,  stringy,  or  other- 
wise unnatural,  or  if  dirt  gets  into  it,  it  shall  be  discarded  and  the  pail 
washed  and  sterilized  before  it  is  again  used. 

Mil  kino  coics  excluded  from  herd.  Cows  separated  from  the  herd 
shall  be  milked  after  the  herd  is  milked  or  by  other  milkers  than  those 
employed  with  the  herd. 

Cooling.  Immediately  after  each  cow  is  milked,  the  milk  shall  be 
taken  to  the  milk  room  for  cooling  and  bottling. 

CONDITION  OF  THE  STABLE  IN  WHICH  THE  MILK  is  DRAWN. 

The  stable  shall  be  kept  scrupulously  clean.  Interior  walls  shall  In- 
light  in  color.  If  whitewash  is  used,  a  fresh  coat  shall  be  applied  at  least 
three  times  a  year,  and  oftener  if  necessary,  to  keep  the  walls  clean  and 
white.  Mold  spots  shall  not  be  permitted. 

Tools,  when  not  in  use,  shall  not  be  exposed  in  the  stable. 

The  stable  shall  be  thoroughly  cleaned  at  least  once  daily.  Neither 
this  nor  other  work  which  would  stir  up  dust  or  odors  shall  be  done 
within  thirty  minutes  before  milking  time. 

While  cows  are  being  cleaned,  the  stable  shall  be  thoroughly  ventilated, 
and  the  floor  may  be  sprinkled  to  reduce  the  dust. 

At  least  once  every  two  months,  the  mangers  shall  be  scrubbed  with  a 
brush  and  soap,  lye,  or  washing  powder. 


162  CERTIFIED  MILK. 

Calves,  dry  cows,  horses,  or  other  animals,  or  chickens,  shall  not  be 
allowed  in  the  stable  with  milking"  cows,  nor  in  anv  adjoining  apartment. 

No  dust}-  or  moldy  hay  or  straw,  bedding  from  horse  stalls,  or  other 
unclean  material  shall  be  used  for  bedding  cows. 

PREPARATION  OF  THE  MILKERS;  THEIR  CLEANING;  THEIR  DRESS. 

A  special  room,  conveniently  located,  shall  be  provided  for  the  milkers 
to  wash  in  before  and  during  milking. 

Employees  shall  be  clean  in  habits  and  appearance. 

Contagious  diseases.  No  person  having  an  inflamed  throat,  or  other- 
wise out  of  health,  shall  be  admitted  to  stable  or  dairy  room. 

The  existence  of  smallpox,  typhoid  fever,  diphtheria,  scarlet  fever, 
measles,  or  other  contagious  disease  on  or  in  the  vicinity  of  the  dairy 
shall  be  immediately  reported  to  the  Commission  by  telephone  or  tele- 
graph, and  the  sale  of  milk  shall  be  subject  to  the  direction  of  the  med- 
ical inspector. 

No  person  connected  with  the  dairy  shall  enter  a  house  where  there  is, 
or  has  been,  a  contagious  disease,  until  same  has  been  disinfected,  and 
no  person  having  entered  such  a  house  shall  enter  upon  the  dairy 
premises. 

While  .  engaged  about  the  dairy  or  in  handling  the  milk,  employees 
shall  not  use  tobacco  or  intoxicating  liquors. 

Hands  of  Milkers. —  Washing'.  Before  milking,  the  milker's  hands 
shall  be  thoroughly  cleaned  by  the  use  of  soap  and  a  brush,  and  then 
rinsed  in  clean  water.  He  shall  be  careful  not  to  touch  anything  but 
the  clean  top  of  a  milking  stool,  the  milking  pail,  and  the  cow's  teats. 
The  hands  shall  be  kept  dry  when  milking. 

Milkers  shall  wear  outer  garments  which  are  washed  at  least  twice  each 
week,  and,  when  not  in  use,  kept,  not  in  a  dwelling,  but  in  a  clean, 
ventilated  place  where  dust  does  not  have  access  and  provided  especially 
for  this  purpose. 

vSHAPE,  PREPARATION,  AND   CONDITION   OK   VESSELS  KOR  RECEIVING 

THE  MILK. 

The  milk  shall  come  in  contact  with  no  vessel  or  apparatus  which  is 
not  clean  and  practically  sterile. 

The  opening  of  the  milking  pail  shall  not  be  larger  than  a  circle  seven 
inches  in  diameter.  A  visor  or  hood  to  further  reduce  the  opening  is 
recommended. 

THE  STRAINING,  COOLING.  AND  BOTTLING  OF  THE  MILK. 

Promptly  after  milk  is  drawn,  it  shall  be  strained  through  a  fine  wire 
gauze  and  a  layer  of  absorbent  cotton,  protected  on  each  side  by  a  piece 
of  cheese  cloth,  or  an  equally  good  strainer. 


AC.KKKMKXT    WITH    DAIRYMEN.  163 

It  shall  be  cooled  at  once  to  50'  I',  or  lower,  and  maintained  below 
50°  F.  until  delivery.  No  ice  shall  be  put  into  the  milk. 

The  milk  shall  be  bottled  promptly,  and  may  be  bottled  before  cool- 
ing, providing  this  system  assures  cooling  within  fifteen  minutes  from 
the  cow. 

Milk  shall  be  stored  only  in  the  milk  room. 

Water  used  for  cooling  or  storage  purposes  shall  be  kept  fresh  and 
free  from  odor. 

No  preservative  or  other  substance  shall  be  added  to  the  milk  for  any 
purpose,  and  no  part  of  the  milk  shall  be  removed  ;  but  the  addition  or 
subtraction  of  cream  may  be  practiced  when  specially  permitted  by  the 
Commission  for  the  purpose  of  producing  milk  of  guaranteed  standard, 
provided  this  does  not  conflict  with  milk  laws  and  ordinances. 

LOCATION  AND  CONDITION  OF  COOUNG  AND  BOTTLING  ROOM. 

The  bottling  room  shall  be  within  easy  access  of  the  stable,  but  so 
placed  that  it  cannot  easily  be  reached  by  dust  or  odors  from  the  stable 
or  yard  or  other  source. 

It  shall  be  used  for  no  other  purpose  than  to  provide  a  place  for  hand- 
ling the  milk,  storing  clean  milk  utensils,  and  holding  fresh  milk  pre- 
vious to  its  removal  from  the  dairy. 

This  room  shall  be  entered  only  by  persons  having  business  therein, 
and  wearing  clean  outer  garments. 

It  shall  be  kept  scrupulously  clean. 

Utensils  shall  be  promptly  removed  after  use  and  cleaned  in  another 
room. 

The  milk  room  shall  be  well  lighted  and  screened,  and  drained  through 
well-trapped  pipes. 

PACKAGES  FOR  THE  TRANSFER  OF  MILK. 

A  flint  glass  bottle  free  from  permanently  attached  parts  shall  be  used 
for  the  delivery  of  milk. 

CLEANSING  OF  MILK  CONTAINERS. 

All  milk  containers  and  utensils  shall  be  thoroughly  cleaned  by, hot 
water  and  salsoda  or  other  equally  pure  agent,  rinsed  until  the  cleaning 
water  is  thoroughly  removed,  then  exposed  to  live  steam  or  boiling  water 
at  least  twenty  minutes,  then  held  until  used  where  dust  and  other  con- 
taminating material  will  not  have  access. 

SEALS. 

Milk  bottles  shall  be  sealed  as  soon  as  possible  after  filling,  and  they 
shall  not  be  opened  before  delivery.  A  satisfactory  seal  consists  of 
melted  paraffine  carefully  poured  over  the  cap  and  impressed  with  date. 

In  addition  to  the  stopper  which  confines  the  milk,  the  lip  of  the  bottle 
shall  be  protected  by  tin  foil  caps  or  heavy  parchment  paper  circles. 


164  CERTIFIKI)  MILK. 

HO\A*  ARK  THK  CAPS  FOR   MlI.K   BOTTIJiS  MARKED? 

Caps  to  close  milk  bottles  shall  be  marked  to  sho\v  the  claimed  quality 
of  the  milk  (or  cream).  On  the  caps  or  elsewhere,  but  accompanying 
each  package,  there  shall  be  stated  the  name  of  producer,  name  of  dealer 
(if  different),  name  of  Commission,  guarantee  of  Commission,  and  expir- 
ing date  of  same. 

i 
TRA  XSPORTATION  . 

At  no  time  between  the  cooling  of  the  milk  and  its  delivery  shall  its 
temperature  be  allowed  to  exceed  50°  F. 

Bxcept  when  the  outdoor  temperature  is  below  freezing,  ice  shall  be 
placed  in  the  bottle  cases. 

Milk  shall  reach  the  consumer  within  thirty  hours  after  production. 

Experts  employed  by  milk  commissions.  In  the  work  of  dairy 
inspection  and  examination  of  the  product,  it  is  usual  to  employ 
four  experts,  a  veterinarian,  a  bacteriologist,  a  chemist  and 
a  medical  examiner.  The  compensation  for  their  services, 
always  paid  by  the  dairyman,  is  collected  in  various  ways. 
Some  commissions  sell  bottle  caps  or  other  distinguishing 
devices  at  a  price  that  covers  the  whole  expense  of  examination, 
about  five  dollars  per  thousand.  Others  have  a  graduated  fee 
roughly  proportional  to  the  output  of  the  dairy.  In  other 
cases  the  dairyman  pays  a  specific  fee  for  each  examination. 
Very  frequently  public  laboratories  are  able  to  make  chemical 
or  bacteriological  examinations  gratis  or  for  nominal  fees. 

Veterinary  inspection.  The  duty  of  the  veterinarian  is  to  de- 
termine the  general  health  of  the  animals,  to  observe  the  sanitary 
conditions  and  to  scrutinize  the  technic  of  milk  handling.  In 
general,  his  duty  is  to  determine  if  the  conditions  of  the  agree- 
ment of  the  dairyman  with  the  commission  are  being  observed. 
His  criticisms  and  suggestions  must  maintain  that  degree  of 
alertness  on  the  part  of  the  foreman  of  milkers  and  other 
employees  that  shall  minimize  the  possibility  of  contamination 
of  the  milk. 

The  control  of  bovine  tuberculosis  is  a  task  that  demands 
the  utmost  vigilance.  Without  care  in  regard  to  this  disease, 
the  pretensions  of  a  certified  dairy  are  fraudulent.  When 
not  rigorously  dealt  with,  it  constitutes  the  greatest  menace  to 
the  financial  success  of  a  certified  dairv.  Tuberculin  tests 


EXPERTS  EMPLOYED   BY   MIUC   COMMISSIONS.  165 

a  year  apart,  with  careless  supervision  of  additions  to  the  herd, 
are  useless  in  a  herd  that  was  badly  infected  at  the  beginning, 
for  tuberculosis  will  keep  pace- with  lax  efforts  directed  against 
it.  It  is  not  sufficient  to  test  merely  the  cows  that  happen  to 
be  in  milk  at  the  time  of  the  test.  Every  dry  cow  should  be 
included.  In  an  infected  herd,  a  test  once  in  six  months  is 
regarded  as  necessary,  followed  each  time  by  thorough  disin- 
fection of  the  stable.  The  control  of  tuberculosis  cannot  be 
accomplished  by  one  test  carried  out  in  a  perfunctory  manner, 
but  the  struggle  must  extend  over  years. 

Additions  to  the  herd  must  be  tested  with  tuberculin,  but 
there  is  always  danger  that  an  animal,  though  not  reacting, 
may  introduce  the  disease.  On  this  account  it  is  far  better  to 
subject  each  animal  added  to  the  herd  to  a  three  months'  quar- 
antine with  a  tuberculin  test  at  the  beginning  and  end  of  this 
period.  During  the  period  the  milk  may  be  used. 

The  details  concerning  the  tuberculin  test  and  management 
of  the  disease  are  given  in  Chap.  IV. 

Bacteriological  examinations.  The  numerical  determination 
of  the  bacteria  in  milk  is  made  every  week  and  constitutes  a  use- 
ful check  upon  the  methods  employed  in  producing  and  hand- 
ling the  milk.  A  low  count  indicates  that  cleanliness  has  been 
observed  in  the  care  of  the  utensils  and  in  milking,  and  that 
the  product  has  been  properly  refrigerated.  The  bacterial 
count  is  made  of  the  milk  when  about  the  age  that  it  ordinarily 
is  when  it  reaches  the  consumer.  Care  should  be  taken  that 
the  sample  be  kept  properly  refrigerated  until  the  examination 
is  made.  The  samples  should  be  taken  from  the  dairyman 
unexpectedly  as  regards  time  and  place.  Thus  it  would  be 
impossible  for  him  to  submit  extra  good  samples  with  fraud- 
ulent intent.  The  numerical  determination  of  the  bacteria  in 
milk  is  a  good  safeguard  against  the  fraudulent  sale  of  ordi- 
nary dirty  milk  under  the  guise  of  certified  milk.  There  is  a 
very  wide  difference  in  the  results  that  are  obtained  by  exam- 
ining the  samples  of  these  two  classes  of  milk  and  thus  fraud 
may  be  detected. 

The  grade  of  milk  designated  "certified"  should  never 
contain  more  than  10,000  bacteria  percc.  If  there  is  a  second 


166  CERTIFIED   MILK. 

grade  known  as  "  Inspected  "  milk,  it  should  not  contain  more 
than  100,000  bacteria  per  cc.  in  summer  and  60,000  bacteria 
per  cc.  in  winter.  It  is  unfortunate  and  confusing'  to  have 
milk  commissions  recognize  two  grades  of  milk.  The  technic 
of  the  bacteriological  examination  of  the  milk  is  described  in 
Chap.  VIII. 

Reporting  on  samples  and  keeping  records  of  results  is  facili- 
tated by  the  use  of  a  3  by  5-inch  card  printed  for  the  reception 
of  data  as  follows  : 

REPORT  OF  NUMERICAL  DETERMINATION  OF  BACTERIA  IN  MILK. 

Dairy.      Reported 

Collected   at Date        Hour... 

Milk  drawn  at (A.  \i.)  (P.M.).     Plated  at.  (A.  M.  )  (  p.  M.) 

Max.  possible  age hrs.     Temperature  when  plated C. 

Colonies  per  cc. Condition  of  package.. 


Chemical  examinations .  Chemical  examinations  are  generally 
made  monthly.  A  committee  of  the  American  Association  of 
Medical  Milk  Commissions  has  made  a  report  on  chemical 
standards,  which  is  very  briefly  abstracted  here  (3).  Milk  rated 
at  4%  fat  should  range  from  3.5%  to  4. 5%,  and  5%  milk  from 
4.5%  to  5.5%.  The  Babcock  test  is  recommended,  but  in  case 
of  condemnation  for  low  fat  control  by  the  ether-extraction 
method  is  desirable. 

Protein  estimations  are  not  recommended  as  a  routine. 

It  is  suggested,  that  regular  tests  be  made  for  formaldehyde 
with  the  sulphuric  acid-ferric  chloride  test,  and  if  the  test  is 
positive,  that  the  specimen  be  distilled  and  the  distillate  tested. 
Borax  and  boric  acid  may  be  looked  for  by  the  turmeric  test. 
Tests  for  salicylic  acid,  benzoic  acid  and  benzoates  may  be 
made  four  times  a  year  at  unexpected  intervals. 

It  is  recommended  that  tests  for  heated  milk  be  regularly 
carried  out  as  a  check  against  the  use  of  undesirable  high  pas- 
teurization temperatures,  which  alone  can  be  detected  by  test. 

Acidity  tests  of  certified  milk  are  of  little  importance.  Like- 
wise, a  specific  gravity  standard  need  not  be  set  for  certified 


TIIK  CKKTIKIKI)  MILK    PACKAGE.  167 

milk.  Routine  tests  for  specific  gravity  should  he  carried  out 
as  a  check  against  gross  adulterations. 

Medical  inspection.  The  health  of  employees  and  of  their 
families  offers  an  important  field  for  the  exercise  of  precau- 
tionary measures.  In  some  cases,  a  weekly  postal  card  report 
concerning  health  conditions  is  required  of  the  dairy  super- 
intendent. The  use  of  diphtheria  swab  examinations  to 
detect  carriers  of  diphtheria  infection  about  a  dairy  has  not 
been  adopted,  but  might  well  be  seriously  considered.  The 
possibility  that  ' '  carriers  ' '  of  both  typhoid  fever  and  diphtheria 
bacilli  may  work  about  a  dairy  without  recognition  by  an  ordi- 
nary examination  is  a  troublesome  feature. 

The  certified  milk  package.  The  fundamental  idea  in  the 
delivery  of  certified  milk  is  to  have  the  milk  bottles  sealed  at 
the  dairy  and  marked  with  a  device  indicating  the  approval  of 
the  commission.  The  Brooklyn  commission  sells  the  dairy- 
men bottle  caps  bearing  a  certification  label,  and  illegitimate 
use  of  them  may  be  prevented  by  taking  care  that  the  consump- 
tion of  caps  does  not  exceed  the  output  of  the  certified  herd. 
After  the  caps  are  affixed  in  the  bottles,  a  layer  of  paraffin  is 
placed  over  the  cap  and  before  it  cools  an  impression  is  made 
with  a  rubber  stamp,  marking  the  date  upon  which  the  milk 
is  to  be  sold  and  used.  The  stamps  are  the  property  of  the 
commission,  and  contain  certain  private  marks  by  which  the 
experts  of  the  commission  may  recognize  the  impression.  The 
stamps  are  assigned  to  different  dairymen  from  time  to  time. 
Other  commissions  issue  slips  bearing  a  statement  concerning 
certification,  which  are  issued  to  the  dairymen  and  placed  over 
the  paper  cap.  Such  a  slip  bears  information  as  follows  :  , 

ST.  LOUIS  PURE  MILK  COMMISSION. 
MILK  COMMISSION  CERTIFICATE. 

Date .... 

Milk  or  cream  from  the  dairy  of .and  the 

dairy  itself  have  been  recently  examined  by  the  experts  of  the  Commis- 
sion and  found  to  be  up  to  the  required  standards  of  excellence.  Another 
examination  will  be  made  within  a  month,  and,  if  satisfactory,  new  labels 
for  the  bottles  will  be  issued  dated  (Notice  the  date.) 


168  CERTIFIED  MILK. 

The  top  and  lip  of  the  bottle  are  protected  by  an  additional 
cap  extending  down  over  the  neck.  This  may  be  of  tinfoil  with 
ornamental  lettering.  Another  device  consists  of  a  6-inch 
circle  or  square  of  parchment  paper  crumpled  around  the  neck 
and  held  in  place  by  a  rubber  band.  The  paper  may  bear  a 
printed  label. 

Certified  milk  may  be  delivered  in  bulk  to  institutions  in 
cans  the  covers  of  which  are  fastened  with  a  lead  seal  distinc- 
tive of  the  certification  of  the  commission. 

Amount  of  certified  milk  produced.  Certified  milk  at  present 
constitutes  a  very  small  percentage  of  the  general  milk  supply. 
Dr.  Coit,  in  his  presidential  address  before  the  American  Asso- 
ciation of  Medical  Milk  Commissions,  held  in  Chicago,  in  1908, 
made  the  following  comment : 

1 '  In  New  York  City,  the  10,000  quarts  of  certified  milk  is  only  one-half 
of  \%  of  the  1,800,000  quarts  consumed  daily,  and  if  every  quart  of  cer- 
tified milk  went  to  a  baby,  which  it  does  not,  it  would  be  less  than  5  ft 
of  all  the  babies  in  New  York  City,  which  is  205,000." 

Certified  milk  has  been  before  the  public  in  New  York  since 
1896,  twelve  years.  The  small  amount  consumed  repre- 
sents the  small  proportion  of  people  in  the  country  now  who 
realize  the  necessity  for  good  milk  and  are  able  to  pay  for  it. 
The  figures  offer  subject  for  thought  in  connection  with  the 
problem  of  educating  the  public  in  the  matter  of  paying  twelve 
to  twenty  cents  a  quart  for  good  milk. 

Certified  milk  is  producing  a  good  effect  in  the  various  com- 
munities where  it  is  known,  out  of 'all  proportion  to  the  amount 
of  such  milk  produced.  It  has  been  a  potent  factor  in  arous- 
ing the  present  wave  of  interest  in  clean  milk  which  is  sweep- 
ing over  the  country  but  is  not  a  response  to  the  demand  for 
pure  milk  for  the  masses. 

Fraudulent  certified  milk.  There  was  an  instance  in  Louis- 
ville, Ky.,  in  \vhich  a  dealer  employed  two  physicians  and  a 
veterinarian  on  salaries  and  sold  milk  under  their  ' '  certifi- 
cation." In  another  case,  milk  was  sold  as  "  certified  milk  " 
on  the  basis  of  a  falsified  tuberculin  test  by  two  disreputable 
veterinarians.  The  difficulty  has  been  met  in  New  York  State 
by  legislative  action  as  follows  : 


MAINTENANCE  OF  STANDARD.  169 

' '  No  person  shall  sell,  exchange  or  offer  or  expose  for  sale,  or  exchange 
as  and  for  '  certified  '  milk,  any  milk  which  does  not  conform  to  the  regu- 
lations prescribed  by,  and  bear  the  certification  of,  a  Milk  Commission 
appointed  by  a  County  Medical  Society  organized  under  and  chartered  by 
the  Medical  Society  of  the  State  of  New  York  and  which  has  not  been 
pronounced  by  such  authority  to  be  free  from  antiseptics,  added  preser- 
vatives, and  pathogenic  bacteria  or  bacteria  in  excessive  numbers.  All 
milk  sold  as  '  certified  '  milk  shall  be  conspicuously  marked  with  the  name 
of  the  Commission  certifying  it." 

In  Kentucky  a  conviction  has  been  obtained  in  the  Circuit 
Court,  under  the  state  pure  food  law,  on  the  ground  that  the 
fraudulent  certified  milk  had  been  so  advertised  as  to  deceive 
and  defraud  the  public.  It  was  established  that  the  term  ' '  cer- 
tified milk  "  had  come  to  have  a  distinctive  meaning.  -In  Cal- 
ifornia, the  institution  of  similar  proceedings  under  the  pure 
food  and  drugs  act  of  that  state  induced  a  dairyman  to  stop 
the  illegitimate  use  of  the  phrase.  Tuley  (13)  has  discussed 
this  problem  thoroughly. 

Infringement  in  the  matter  of  the  use  of  .the  term  *•'  certified 
milk"  cannot  do  very  much  harm,  for  it  is  a  simple  matter 
for  a  medical  milk  commission  to  notify  the  profession  and 
the  public  of  the  fraudulent  nature  of  the  claims. 

Maintenance  of  standard.  That  the  milk  produced  in  a 
number  of  certified  dairies  is  really  what  it  is  claimed  to  be  by 
the  milk  commissions  controlling  those  dairies  has  been  shown 
in  an  investigation  conducted  by  the  Dairy  Division  of  the 
U.  S.  Department  of  Agriculture. 

Sixteen  dairies  were  visited  and  scored  by  a  representative 
of  the  department.  The  average  score  was  93.4  on  a  scale  of 
100  (perfection).  The  average  score  of  several  details  was  as 
follows  :  Cows,  99.5  ;  stable,  87.2  ;  milk  house,  94.5  ;  milking, 
94.0;  handling  of  milk,  93.0.  It  should  be  noted  that  the 
high  score  of  the  cows  was  based  largely  upon  credit  given  for 
the  tuberculin  test  required  by  all  commissions,  but  which  was 
not  made  by  the  Department  of  Agriculture. 

Twelve  samples  of  certified  milk  (four  days  old)  were  scored, 
with  an  average  of  86.0.  The  bacterial  count  varied  from  280 
to  19,000  per  cc.  (8). 


170  CERTIFIED  MILK. 

Milk  dispensaries.  In  France,  the  decreasing  birth  rate  first 
stimulated  an  interest  in  agencies  for  decreasing  the  death  rate 
of  infants.  One  form  of  institution  called  "consultation  dc 
nourrisons  "  is  attached  to  maternity  hospitals.  Children  born 
in  the  hospital  are  kept  under  medical  supervision  for  two  years. 
They  are  brought  to  the  hospital  once  a  week,  weighed,  and 
medical  advice  is  given  the  mother.  A  slightly  different  sort 
of  institution,  goittte  de  /ait  (milk  dispensary),  furnishes  milk 
to  the  poor  in  general. 

In  the  work  of  milk  dispensaries  the  aim  is  to  decrease  infant 
mortality  among  the  poor  by  remedying  methods  of  care  and 
feeding.  Breast  feeding  is  urged,  but  when  this  is  impossible, 
a  pure  supply  of  milk  is  provided.  When  the  circumstances 
demand,  the  milk  is  modified  to  meet  the  requirements  of  the 
individual  infant.  Instruction  in  the  proper  hygienic  care  of 
infants  is  recognized  as  quite  as  important  as  pure  food.  This 
is  accomplished  most  effectively  by  oral  instruction,  supple- 
mented by  educational  pamphlets. 

Milk  dispensaries  are  maintained  in  about  twenty  cities  in 
the  United  States.  In  ten  of  these,  the  milk  is  pasteurized  at 
various  temperatures.  In  six  cases  certified  milk  is  used  and 
in  the  others  milk  from  good  sources.  In  general  the  milk 
dispensaries  are  maintained  during  the  summer  only,  but  in 
some  cases  they  are  open  during  the  whole  year.  Milk  dis- 
pensaries are  maintained  as  charities.  Nathan  Straus  of  New 
York  is  particularly  active  in  this  form  of  philanthrophy.  Out 
of  the  twenty  cities  in  which  there  are  milk  depots,  only  four 
of  them  are  maintained  at  the  expense  and  under  the  super- 
vision of  the  health  department. 

There  are  so  many  factors  involved  that  it  is  impossible  to 
place  a  valuation  upon  the  influence  of  the  clean  milk  alone, 
even  though  the  work  of  milk  dispensaries  is  an  important 
factor  in  reducing  infant  mortality  (9,  10). 

Rochester,  A\  }\ ,  ;;////•  dispensaries.  Dr.  Goler,  the  Health 
Officer  of  Rochester,  N.  Y.,  has  established  milk  depots  under 
the  control  of  the  health  department.  A  contract  is  made  for 
the  product  of  a  dairy  during  two  months  in  the  summer. 
A  temporary  laboratory  is  established  at  the  farm  and  em- 


^Vf 

^- —  ,f- JI.».«T, 


MILK  DISPENSARIES. 


171 


<j7  c™j  su? 

di    ii     U 


Jan 


feb 


mar 


Opr 


may 


Jun     I  July 


Pug 


Ckl 


Dec 


Soo 


\ 


\ 


\ 


/'/{,'.  77.     C/icii'f  Showing  relation  of  municipal  milk  stations  to  infant 

mortality  (6). 


172  t  CERTIFIED  MILK. 

ployees  of  the  department  supervise  the  production  of  the  milk, 
and  take  charge  of  it  immediately  after  drawing.  The  various 
modifications  are  made,  and  the  product  is  shipped  in  the 
nursing  bottles  to  the  various  city  dispensing  stations.  There 
are  four  of  these  stations,  each  in  charge  of  a  trained  nurse. 
The  instruction  in  the  care  of  infants  is  facilitated  by  pamph- 
lets printed  in  English,  German,  Italian  and  Yiddish. 

Fig.  17  by  Goler  (6)  shows  the  beneficial  effects  resulting 
from  the  establishment  of  milk  stations.  The  work  is  accom- 
plished for  a  season  of  two  months  at  an  expense  of  about  one 
thousand  dollars  a  year.  The  system  of  control  of  the  pro- 
duction of  the  milk  makes  it  possible  to  use  raw  milk  (5,  6). 

The  practicability  of  municipal  control  of  milk  .stations  has 
been  demonstrated,  and  there  is  every  reason  for  the  adoption 
of  this  line  of  work  by  other  municipalities. 


REFERENCES. 

1.  AMERICAN  ASSOCIATION  OF  MEDICAL  MILK  COMMISSIONS.     Pro- 
ceedings of  the   first  annual   session.     Published   by  the  Secretary,   Dr. 
Otto  P.  Geier,  124  Garfield  Place,  Cincinnati,  Ohio,  1907. 

2.  CoiT.     A  brief  history  of  the  development  of  the  pure  milk  move- 
ment in  the  United  States.     Paper  read  at  the   Congres  Internationale 
des  Gouttes  de  Lait,  Brussels,  1907. 

2  a.  CoiT.  Clean  milk  in  its  economic  and  medical  relations  with 
special  reference  to  certified  milk.  Kentucky  State  Medical  JouruaL 
May,  1908. 

3.  EBSALL,  VAN  SLYKE  and  CHAPMAN.     Report  of  the  committee  on 
chemical  standards.     Pediatrics,  Vol.  XX,  1908,  No.  7,  p,  455. 

4.  GiER.     Our  experience  with  certified  milk  in  Cincinnati.    Kentucky 
Med.  Jour.,  Vol.  VI,  1908,  p.  276. 

5.  GOLER.     But  a  thousand  a  year.     Charities,  August  5,  1905. 

6.  GoLER.     Scheme  for  the  sanitary  control  of  the  municipal  milk 
supply.     Paper  read  at  the  Congres  Internal ionale  des  (.>outtes  de  Lait , 
Paris,  1905. 

7.  KERR.      Certified    milk  and    infants'   milk  depots.     Bui.  Xo.  41, 
Hyg.  Lab.,  U.  S.  Pub.  Health  and  Mar.  Hasp.  Sen'.,  Washington,  D.  C., 
1908,  p.  565. 


RKPKRKXCKS.  173 

8.  lyANK.     Medical  milk  commissions  and  the  production  of  certified 
milk  in  the  United  States.      Jiiil.  \o.  10f,  I>itr.  Auini.  hid.,  f '.  .V.  /)r/>/. 
Agr.,  Washington,  D.  C.,  1908. 

9.  McCi^KARV.     Infant  mortality  and  infants' milk  depots.     London: 
P.  S.  King  &  vSon,  1905. 

10.  McCivKARY.     The  infants'  milk  depot.     Its 'history  and  function. 
Jour.  //K<f->  Vol.  IV,  1904,  p.  329. 

11.  PKARSON,  LKONARD.     Report  of  the  committee  on  the  inspection 
of  herds  and  farms  used  for  the  production  of  certified  milk.     Pediatrics, 
Vol.  XX,  1908,  No.  8,  p.  500. 

12.  PKARSON,    R.    A.     Market   milk:  A   plan   for  its  improvement. 
Seventeenth  Ann.  Rept.  Bur.  Anim.  Ind.,  f  T.  S.  Dept.  Agr.,  Washing- 
ton, D.  C.,  1900,  p.  158. 

13.  TuivEY.     legislation  as  a  factor  in  the  production  of  clean  milk. 
Pediatrics,  Vol.  XX,  1908,  No.  8,  p.  487. 

14.  WARD.     Milk  production  under  hygienic  conditions.     Occidental 
Medical  Journal,  Vol.  XVI,  1902,  p.  178. 


CHAPTER  X. 


THE  ANALYSIS  OF  MILK. 


Introduction.  In  addition  to  the  data  obtained  from  the 
sanitary  inspection  of  dairies,  the  health  officer  should  be  in  a 
position  to  inform  himself  as  to  the  composition  of  the  milk  as 
sold.  It  is  with  a  view  to  supplying"  such  necessary  aid  that 
these  two  chapters  are  here  presented.  It  is  not  intended  to 
offer  full  and  complete  details  for  the  analysis  of  milk  but  rather 
to  give  some  simple  and  at  the  same  time  accurate  and  reliable 
tests  for  ascertaining  not  only  the  fat  content  but  also  whether 
or  not  a  milk  has  been  in  any  way  sophisticated.  For  further 
details  the  reader  is  directed  to  the  standard  works  mentioned 
at  the  end  of  the  chapter. 

Composition  of  milk.  Normal  cow's  milk  contains  water 
and  the  four  nutrients,  protein,  fat,  carbohydrate  and  ash  or 
mineral  matter. 

Protein.  Casein  is  the  chief  proteid  of  milk,  constituting 
fully  80%  of  the  total  amount,  the  next  in  importance  being 
albumen  present  to  the  amount  of  15f/r .  The  remaining  5'/r 
consists  of  different  nitrogenous  compounds,  as  lactoglobulin, 
galactin,  fibrin,  etc. 

The  protein  content  of  normal  herd  milk  does  not  vary 
greatly,  but  that  of  individual  cows  has  been  known  to  range 
from  2.07%  to  6.69'/<  . 

Fat.  This  is  the  most  variable  ingredient  of  milk.  It  does 
not  occur  in  solution  but  is  found  suspended  in  the  form  of 
minute  globules.  These  vary  in  size  not  only  with  the  milk  of 
the  different  breeds  but  also  with  the  same  breed  or  individual 
during  the  period  of  lactation.  It  is  a  well  known  fact  that 
the  Channel  Island  breeds,  Jerseys  and  Guernseys,  yield  milk 
showing  the  highest  fat  content  and  the  Holstein-Friesian 
cattle  as  a  rule  produce  milk  of  a  low  fat  content. 


COMPOSITION  OF  MILK. 


175 


The  fat  percentage  of  milk  not  only  varies  with  the  differ- 
ent breeds  but  also  in  different  portions  of  the  same  milking, 
as  shown  in  the  following  table  from  Aikman  (l). 

TABLE  vii. 

VARIATION  OF  SOLIDS  IN  DIFFERENT  PORTIONS  OF  ONE  MILKING. 


PORTION. 

FIRST. 

SlCCOND. 

THIRD. 

FOURTH. 

FIFTH. 

SIXTH. 

Per  cent. 

Percent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Total  solids 

10.47 

10.75 

10.85 

11.23 

11.63 

12.67 

Fat 

1.70 

1.76 

2.10 

2.54 

3.14 

4.08 

Solids  not  fat 

8.77 

8.99 

8.75 

8.69 

8.49 

8.59 

It  must  be  borne  in  mind  that  in  mixed  herds  the  product 
varies  in  fat  percentage  to  a  considerable  degree.  Some  bot- 
tles or  even  cans  will  be  unnecessarily  rich  in  fats  at  the 
expense  of  others  which  will  run  below  standard.  This  cir- 
cumstance may  result  in  the  condemnation  of  the  milk,  due 
entirely  to  careless  manipulation,  when  the  average  of  the  herd 
may  be  entirely  satisfactory.  The  whole  output  of  a  herd  at 
one  milking  is  not  mixed  in  one  receptacle  and  then  trans- 
ferred to  cans  or  bottles.  The  usual  practice  is  to  take  the 
milk  of  a  few7  cows  at  a  time  for  bottling.  Even  under  these 
circumstances  there  is  danger  that  the  fat  will  rise  in  the  vat 
under  the  cooler  unless  the  milk  is  bottled  immediately  after 
cooling.  Too  much  emphasis  cannot  be  placed  upon  this 
important  point  in  the  handling  of  any  milk  and  especially 
with  reference  to  the  product  of  certified  dairies.  This  milk; 
so  frequently  modified  for  infant  feeding,  should  be  of  uniform 
composition. 

The  difficulties  encountered  are  best  obviated  by  alternating 
in  the  stable,  or  in  the  order  of  milking,  the  cows  known  to 
yield  milk  of  high  fat  content  with  those  known  to  give  poor 
milk.  In  the  case  of  the  Channel  Island  breeds  and  the 
Holstein-Friesians  this  is  a  simple  matter.  In  the  case  of 
scrub  cows  this  recognition  may  not  be  so  easy -and  depend- 
ence must  be  placed  upon  the  results  of  the  examination  of  the 
milk  of  these  cows  for  fat  by  the  Babcock  test. 


176 


THE  ANALYSIS  OF  MILK. 


Carbohydrates.  Milk  sugar,  the  carbohydrate  of  milk,  con- 
stitutes between  4.5%  and  5%  of  the  milk. 

Mineral  matter.  The  ash,  as  stated  by  Leach  (2),  does  not 
represent  the  true  mineral  content  of  milk,  since  in  the  process 
of  incineration  some  of  the  constituents  are  altered.  For 
instance,  citric  acid  occurring  hi  small  quantities  in  normal 
milk  will  appear  in  the  ash  as  carbonic  acid  in  combination. 
Several  other  illustrations  could  be  given. 

The  ash,  in  all  probability,  is  the  least  variable  of  any  of  the 
ingredients  of  milk  and  for  that  reason  is  often  made  the  basis 
of  calculating  the  composition  of  an  original  milk  from  the 
analytical  results  of  the  examination  of  a  condensed  milk. 

Solids  of  milk.  The  protein,  fat,  sugar  and  ash  comprise 
what  are  designated  as  milk  solids.  The  sugar,  protein  and 
mineral  matter  constitute  the  solids  not  fat.  These  latter,  with 
the  water,  are  known  as  the  milk  serum. 

The  average  composition  of  milk,  its  derivatives  and  colos- 
trum, are  shown  in  the  following  table. 

TABLE  VIII. 
COMPOSITION  OF  MILK,    ETC. 


CONSTITUENTS 

WATER. 

FAT. 

SUGAR. 

PROTEIN. 

ASH. 

AUTHORITY. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Milk  

87.3 

3.6 

4.6 

3.8 

.7 

Babcock. 

Skim-milk.. 

90.3 

.1 

5.2 

3.6 

.8 

Van  vSlvke. 

Buttermilk  .. 

91.0 

.5 

4.8 

3.0 

.7 

Atwater. 

Cream  

68.8 

22.7 

4.2 

3.8 

.5 

Ko'nig. 

Colostrum  .... 

74.5 

3.6 

2.7 

17.6 

1.6 

Konig. 

Effect  of  feeding  on  the  composition  of  milk.  The  idea  is 
prevalent  among  dairymen  throughout  the  country  that  the 
quality  of  the  milk  may  be  improved  by  modification  of  the 
feeding  of  the  cows.  The  problem  has  been  investigated  many 
times  by  eminent  authorities.  Conclusions  have  been  reached 
as  follows  : 

1 .  If  a  cow  is  being  properly  fed,  that  is,  receiving  a  balanced 
ration  suitable  for  her  individual  needs,  the  quality  of  the  milk 


SAMPLING    MILK.  177 

is  not  appreciably  affected  by  an  increase  of  any  of  the  ingred- 
ients of  the  ration. 

2.   Under  such  circumstances  fat  cannot  be  fed  into  milk. 

Sampling'  milk.  The  first  consideration  in  the  examination 
of  milk  is  the  sampling.  It  is  of  the  utmost  importance  that 
a  representative  sample  be  taken  and  too  much  emphasis  can- 
not be  placed  on  this  point.  Great  care  is  called  for  in  samp- 
ling milk  because,  as  previously  stated,  the  fat  of  milk  is  not 
in  solution,  but  held  in  suspension,  and  forms  an  emulsion 
with  the  milk  serum.  The  little  globules  of  fat  commence 
to  rise  very  soon  after  milk  is  allowed  to  stand  and,  to  the 
uninitiated,  surprisingly  fast.  The  writer  has  analyzed  three 
different  samples  of  milk  from  the  same  herd  showing  respect- 
ively 2.9%,  9.1%  and  3.6%  fat.  The  variations  were  due  en- 
tirely to  improper  sampling.  The  sample  should  be  taken  and 
the  examination  conducted  while  the  milk  is  fresh  and  in  normal 
condition.  If  the  samples  are  to  be  transported  to  any  distance 
previous  to  being  tested,  care  should  be  taken  to  see  that  the 
bottles  are  completely  filled.  This  will  avoid  the  tendency  to 
churn  which  might  cause  the  fat  to  collect  in  lumps  and  pre- 
vent, at  times,  an  accurate  determination  of  the  fat. 

After  a  sample  is  properly  taken  it  should  be  thoroughly 
mixed  before  it  is  tested  and  the  respective  portions  for  the 
different  tests  should  be  measured  immediately  after  mixing. 
If  such  a  practice  is  not  adopted,  serious  inaccuracies  are  liable 
to  occur,  owing  to  the  rapidity  with  which  the  fat  globules  will 
rise  toward  the  surface.  By  far  the  best  way  to  mix  a  sample 
is  to  pour  it  from  one  vessel  to  another,  and  the  pouring  should 
be  done  on  the  side  of  the  vessel  and  not  in  the  center.  If  this 
precaution  is  not  taken  an  appreciable  amount  of  air  will  be 
incorporated  in  the  milk,  which  will  greatly  interfere  with  the 
accurate  measuring  of  the  milk  for  the  Babccck  test  for  fat. 

There  are  on  the  market  several  different  devices  for  sam- 
pling market  milk,  such  as  the  Scovell,  McKay,  and  Equity 
sampling  tubes,  etc.  These  with  full  directions  for  use  may 
be  obtained  from  dairy  supply  houses. 

Specific  gravity.  The  specific  gravity  of  a  thoroughly  mixed 
sample  may  be  most  conveniently  taken  by  means  of  the  small 


178 


THE  ANALYSIS  OF  MILK. 


hydrometer  with  the  thermometer  attached.  This  is  about 
seven  inches  long  and  has  a  range  of  from  1.000  to  1.060. 
There  are  several  different  forms  of  lactometers  on  the  market 
but  they  are  not  any  better  adapted  for  milk  than  is  the  hydrom- 
eter to  which  reference  has  just  been  made.  All  readings 
should  be  made  whenever  possible  at  60°  F.  (15.6°C.).  When- 
ever this  cannot  be  done  correction  must  be  made  in  accordance 
with  the  table  below,  taken  from  Richmond  (12). 

TABLE  IX. 
FOR  CORRECTING  SPECIFIC  GRAVITY  TO  60°F. 


J* 

DEGREES  OF  SPECIFIC  GRAVITY  OBSERVED. 

25 

26 

27 

28 

29 

30 

31    i    32 

33 

34 

35 

36 

ft 

Specific  Gravity  corrected  to  60°F. 

40 

23.5 

24.5 

25.5 

26.4 

27.3 

28.2 

29.1 

30.0 

31.0 

31.9 

32.8 

33.7 

42 

23.6 

24.6 

25.6 

26.5 

27.5 

28.4 

29.3 

30.2 

31.1 

32.0 

32.9 

33.9 

44 

23.8 

24.8 

25.8 

26.7 

27.7 

28.6 

29.5 

30.4 

31.3 

32.2 

33.1 

34.1 

46 

23.9 

24.9 

25.9 

26.8 

27.8 

28.7 

29.6 

30.5 

31.4 

32.4 

33.3 

34.3 

48 

24.0 

25.0 

26.0. 

26.9 

27.9 

28.8 

29.7 

30.6 

31.6  32.6 

33.5 

34.5 

50 

24.1 

25.1 

26.1 

27.0 

28.0 

29.0 

29.9 

30.9 

31.8    32.8 

33.7 

34.7 

52 

24.3 

25.2 

26.2 

27.2 

28.1 

29.1 

30.1 

31.1 

32.0 

33.0 

33.9 

34.9 

54 

24.5 

25.4 

26.4 

27.4 

28.4 

29.3 

30.3 

31.3 

32.3 

33.3 

34.2 

35.1 

56 

24.6 

25.6 

26.7 

27.6 

28.6 

29.6 

30.5 

31.51  32.  5 

33.5 

34.4 

35.4 

58 

24.8 

25.8 

26.8 

27.8 

28.8 

29.8 

30.8 

31.7 

32.7 

33.7 

34.7 

35.7 

60 

25.0 

26.0 

27.0 

28.0 

29.0 

30.0 

31.0 

32.0 

33.0 

34.0 

35.0 

36.0 

62 

25.2 

26.2 

27.3 

28.3 

29.3 

30.3 

31.3 

32.3 

33.3 

34.3 

35.3 

64 

25.4 

26.5 

27.5 

28.5 

29.5 

30.5 

31.5 

32.6 

33.6 

34.6 

35.6 

66 

25.6 

26.7 

27.7 

28.7 

29.8 

30.8 

31.8 

32.9 

33.9 

34.9 

35.9 

68 

25.9 

27.0 

28.0 

29.0 

30.1 

31.1 

32.1 

33.2 

34.2 

35.2 

36.2 

70 

26.1 

27.2 

28.2 

29.2 

30.3 

31.3 

32.4 

33.4 

34.5 

35.5 

36.5 

72 

26.4 

27.4 

28.4 

29.5 

30.5 

31.6 

32.6 

33.7 

34.7 

35.8 

74 

26.6 

27.7 

28.7 

29.7 

30.8 

31.9 

32.9 

34.0 

35,0 

36.1 

76 

26.9 

27.9 

28.9 

29.9 

31.0 

32.2 

33.3 

34.4 

35.4 

36.5 

78 

27.2 

28.2 

29.2 

30.3 

31.4 

32.5 

33.6 

34.7 

35.8 

36.9 

80 

27.4 

28.4 

29.5 

30.6 

31.7 

32.8 

33.9 

35.0 

36.0 

The  specific  gravity  of  milk  from  normal,  healthy  cows  will 
vary  from  1.029  to  1.035  at  60°  F  (15.6°  C).  The  average  for 
normal  milk  as  determined  by  the  writer  from  a  large  number 
of  samples  agrees  well  with  the  figures  obtained  elsewhere, 
namely  1.032.  Too  much  stress  cannot  be  placed  on  the  spe- 
cific gravity  determination,  because  it  is  a  simple  matter  to  add 


DETERMINATION  OF  FAT  IN  MILK  AND   CREAM.  179 

water  to  milk  and  then  some  easily  soluble  material  to  bring 
the  gravity  back  to  the  normal.  Nevertheless,  the  determin- 
ation of  the  gravity  is  of  great  assistance  to  the  health  officer 
and  physician. 

The  use  of  the  determination  of  the  specific  gravity  in  the 
detection  of  added  water  is  discussed  in  Chap.  XI. 

Determination  of  fat  in  milk  and  cream,  Fat  being  the  most 
variable  ingredient  of  milk,  it  is  only  logical  that  all  commer- 
cial transactions  relative  to  milk  should  be  based  upon  the  fat 
content.  It  was  this  that  gave  the  incentive  to  a  number  of 
agricultural  chemists  twenty  years  ago,  upon  the  establish- 
ment of  the  agricultural  experiment  stations,  to  devise  a  simple, 
rapid  and  accurate  method  for  the  determination  of  fat,  which 
could  be  intelligently  used  by  those  who  either  had  no  training 
in  chemistry  or  could  not  obtain  access  to  a  chemical  laboratory. 
The  method  now  in  common  use  is  the  one  given  free  to  the 
public  in  1890  by  Dr.  S.  M.  Babcock  of  the  Wisconsin  Agri- 
cultural Experiment  Station.  The  details  of  this  adrnirable 
test  are  hardly  called  for  here  ;  for  such,  and  other  valuable 
and  useful  data,  the  reader  is  referred  to  that  excellent  little 
work,  "Testing  Milk  and  Its  Products,"  by  Farrington  and 
Woll  (5).  Also,  to  "  Modern  Methods  of  Testing  Milk  and 
Milk  Products,"  by  Van  Slyke  (14). 

It  may  be  said,  however,  in  supplementing  the  directions 
usually  given  for  this  test  that  the  addition  of  2  cc.  of  an  80% 
solution  of  glycerin,  as  recommended  by  Holm  (7),  to  the  milk 
in  the  test  bottle  just  previous  to  adding  the  acid  will  insure 
a  clearer  line  of  demarcation  than  is  ordinarily  obtained  be- 
tween the  fat  and  water  in  the  graduated  neck  of  the  bottle; 

Another  modification  which  has  proved  useful  in  the  testing 
of  cream  by  the  Babcock  method  is  that  obtained  by  Kckles 
and  Wayman  of  the  Dairy  Department  of  the  University  of 
Missouri.  It  consists  in  dropping  a  small  quantity  of  amyl 
alcohol  colored  with  fuchsin  or  any  red  dye  on  top  of  the  col- 
umn of  butter  fat  before  it  is  read.  Since  it  is  lighter  than  the 
fat,  it  floats  on  the  surface.  This  removes  the  meniscus  from 
the  surface  of  the  fat  to  the  top  of  the  amyl  alcohol,  and  leaves 
a  perfectly  straight  line  across  the  top  of  the  fat  column.  Thus 


180  THE  ANALYSIS  OF  MILK. 

the  reading"  of  the  fat  is  made  more  accurately  than  when  an 
attempt  is  made  to  read  either  to  the  bottom  or  center  of  the 
meniscus. 

It  is  best  to  read  the  fat  column  immediately  after  the  addi- 
tion of  the  alcohol,  because,  if  the  latter  is  allowed  to  remain 
in  the  fat  column  for  several  hours,  it  mixes  with  the  fat  to  a 
certain  extent  and  the  reading  cannot  then  be  taken  accurately  ; 
but  this  does  not  occur  short  of  two  hours.  This  modification 
has  proven  of  great  assistance  in  the  manipulation  of  the  Bab- 
cock  test  for  the  determination  of  fat  in  cream  and  gives  results 
which  compare  very  favorably  with  the  gravimetric  method  and 
the  ordinary  way  of  reading  the  fat  column  in  the  Babcock 
bottle.  Webster  (15)  has  made  a  very  exhaustive  study  of 
the  testing  of  fat  in  cream  by  the  Babcock  test. 

In  the  hands  of  a  competent  operator,  the  Babcock  test  gives 
as  reliable  and  accurate  results  as  those  obtained  by  the  com- 
plicated ether  extraction  method. 

Interpretation  of  specific  gravity  and  fat.  It  is  almost  impos- 
sible to  lay  down  any  hard  and  fast  rules  concerning  the  inter- 
pretation to  be  placed  upon  the  specific  gravity  and  fat  content. 
It  may  be  said  in  general  with  reference  to  milk  from  herds  in 
normal  condition  that  : 

1.  High  gravity  with  high  fat  content  indicates  a  rich  milk. 

2.  High  gravity  with   low  fat  content   indicates    either  a 
poor  milk  or  that  the  milk  has  been  skimmed. 

3.  Low  gravity  with  high  fat  content  indicates  ' '  top  milk, ' ' 
that  is,   the  sample   has  been   taken   from  a  quantity  of  milk 
which  has  been   allowed  to  stand   some  time  previous  to  sam- 
pling. 

4.  Low  gravity,  in   connection  with  low  fat   content,  indi- 
cates a  watered  milk. 

Solids  not  fat.  While  it  is  true  in  many  instances  that  the 
fat  per  cent,  and  specific  gravity  are  sufficient  to  enable  the 
inspector  to  judge  of  the  quality  of  milk,  at  the  same  time  it 
is  a  simple  matter  to  obtain  the  solids  not  fat  by  calculation. 
Formulas  for  such  calculation  have  been  worked  out  by  Bab- 
cock, Fleischmann,  Richmond  and  others.  The  one  in  general 
use  in  this  country  is  Babcock 's  formula. 


TABLE  X. 
PER    CENT.    OF    SOLIDS   NOT    FAT,    CORRESPONDING   TO   0   TO   6 

PER  CENT.  OF  FAT,  AND  SPINDLE  READINGS  OF  26  TO  36. 
SPINDLE  READINGS  AT  60°  F.  Z^ZZHZZ^Z! 

26   27   28   29   30   31   32   33   34   35   36 


0.0 

6.50 

6.75 

7.00 

7.25 

7.50 

7-75 

8.00 

8.25 

850 

8.75 

9-00 

0.0 

0.1 

6.52 

6.77 

7.02 

7.27 

7-52 

7-77 

8.02 

827 

852 

8-77 

9-02 

0.1 

0.2 

6.54 

6.79 

•7.04 

7.29 

7.54 

7-79 

8.04 

8.29 

8.54 

•879 

9-04 

0.2 

0.3 

6.56 

6.81 

7.06 

7.31 

7.56 

781 

8.06 

831 

8.56 

881 

9-06 

0.3 

0.4 

6.58 

6.83 

7.08 

7.33 

7.58 

783 

8.08 

8.33 

858 

8.83 

9-08 

0.4 

0.5 

6.60 

6.85 

7.10 

7.35 

7.60 

785 

810 

8.35 

860 

8.85 

9-10 

0.5 

0.6 

6.62 

6.87 

7.12 

7.37 

7.62 

787 

8.12 

8.37 

862 

8.87 

9.12 

0.6 

(.7 

6.64 

6.89 

7.14 

7-39 

7.64 

7-89 

8.14 

839 

864 

8.89 

914 

0.7 

O.S 

6.66 

6.91 

7.16 

7-41 

7.66 

7-91 

8.16 

8.41 

8.66 

8.91 

916 

0.8 

0.9 

6.68 

6.93 

7.  IS 

7.43 

7-68 

7-93 

818 

843 

868 

8-93 

918 

0.9 

.0 

6.70 

6.95 

7.20 

7-45 

7-70 

795 

8.20 

8.45 

8.70 

895 

9-20 

1.0 

.1 

6.72 

6.97 

7.22 

7-47 

7-72 

797 

8.22 

8.47 

872 

8-97 

9.22 

1.1 

.2 

6.74 

6.99 

7.24 

7.49 

7-74 

7-99 

824 

849 

874 

8.99 

9.24 

1.2 

.3 

6.76 

7.01 

7.26 

7.51 

7-76 

801 

8.26 

851 

8.76 

901 

9.26 

1.3 

.4 

6.78 

7.03 

7.28 

7.53 

7-78 

803 

828 

853 

878 

9-03 

928 

1.4 

.5 

6.80 

7.05 

7.30 

7.55 

7.80 

805 

830 

8.55 

880 

905 

9-30 

1.5 

.6 

6.82 

7.07 

7.32 

•7.57 

7.82 

807 

832 

8.57 

882 

9-07 

9  S2 

1.6 

.7 

6.84 

7.09 

7.34 

7.59 

7.84 

8.09 

834 

859 

884 

9-09 

9,34 

1.7 

.8 

6.86 

7.11 

7.36 

7.61 

7.86 

8J1 

8.36 

8.61 

886 

911 

937 

1.8 

.9 

6.88 

7.13 

7.38 

7.63 

7.88 

8.13 

838 

863 

888 

9.13 

939 

1.9 

2.0 

6.90 

7.15 

7.40 

7-65 

7.90 

815 

8.40 

866 

891 

9.16 

9-41 

2.0 

2.1 

6.92 

7.17 

7.42 

7.67 

7.92 

817 

842 

868 

893 

918 

943 

2.1 

2.2 

6.94 

7.19 

7.44 

7-69 

7-94 

8.19 

8.44 

8.70 

895 

9-20 

945 

2.2 

2.3 

6.96 

7.21 

7.46 

7-71 

7-96 

821 

846 

8.72 

897 

922 

9  47 

2.3 

2.4 

6.98 

7.23 

7.48 

7-73 

7-98 

823 

8.48 

8.74 

899 

9,24 

949 

2.4 

2.5 

7.00 

7.25 

7.50 

7-75 

8.00 

8.25 

850 

876 

901 

9.26 

951 

2.5 

2.6 

7.02 

7.27 

7.52 

7-77 

8.02 

827 

852 

878 

903 

9  28 

953 

2.6 

2.7 

7.04 

7.29 

7.54 

7-79 

8.C4 

8.29 

854 

880 

905 

930 

955 

2.7 

2.8 

7.06 

7.31 

7.56 

7.81 

8.06 

831 

8.57 

882 

907 

932 

9-57 

2.8 

2.9 

7.  OS 

7.33 

7.58 

7.83 

8.08 

833 

858 

8.84 

909 

934 

9-59 

2.9 

3.0 

7.10 

7.35 

7.60 

7.85 

8.10 

8.36 

8.6l 

8.86 

9  11 

9  36 

9-61 

3.0 

3.1 

7.12 

7.37 

7.62 

7.87 

8.13 

838 

863 

8.88 

913 

938 

964 

3.1 

3.2 

7.14 

7.39 

7.64 

7.89 

8.15 

8.40 

865 

890 

915 

941 

9.66 

3.2 

3.3 

7.16 

7.41 

7.66 

7-92 

8.17 

842 

8.67 

892 

918 

943 

968 

3.3 

3.4 

7.18 

7.43 

7.69 

7.94 

8.19 

8.44 

869 

894 

9-20 

9-45 

9-70 

3.4 

3.5 

7.20 

7.45 

7.71 

7-96 

8.21 

846 

8*71 

8.96 

922 

9-47 

9.72 

3.5 

3.6 

7.22 

7.48 

7-73 

7-98 

8.23 

8.48 

873 

898 

924 

949 

974 

3.6 

3.7 

7.24 

7.50 

7.75 

8.00 

8.25 

850 

8:5 

900 

926 

9-51 

976 

3.7 

3.8 

7.26 

7.52 

7-77 

8.02 

8.27 

852 

877 

902 

9-28 

9-53 

978 

3.8 

3.9 

7.28 

7.54 

7-79 

8.04 

8.29 

8.54 

8.79 

904 

930 

955 

980 

3.9 

4.0 

7.30 

7.56 

7-81 

8.06 

8.31 

856 

881 

9.06 

932 

957 

9-83 

4.0 

4.1 

7.32 

7.58 

7.83 

8.08 

8.33 

858 

8.83 

908 

934 

959 

9-85 

4.1 

4.2 

7.34 

7.60 

7.85 

8.10 

8.35 

8.60 

885 

911 

936 

962 

987 

4.2 

4.3 

7.36 

7.62 

7-87 

8.12 

8.37 

862 

8.88 

9.13 

9-38 

964 

989 

4-3 

4.4 

7.38 

7.64 

7.89 

8.14 

8.39 

864 

890 

9.15 

9.40 

966 

991 

4.4 

4.5 

7.40 

7.66 

7.91 

8.16 

8.41 

8.66 

8.92 

9.17 

942 

968 

993 

4.5 

4.6 

7.43 

7.68 

7.93 

8.18 

8.43 

8.68 

894 

9.19 

9-44 

970 

995 

4.6 

4.7 

7.45 

7.70 

7.95 

8.20 

8.45 

8.70 

896 

9.21 

9.46 

9.72 

997 

4.7 

4.8 

7.47 

7.72 

7.97 

8.22 

8.47 

872 

8.98 

9.23 

948 

9-74 

9-99 

4-8 

4.9 

7.49 

7.74 

7.99 

8.24 

8.49 

8.74 

9-00 

9.25 

9-50 

976 

10.01 

4-9 

5.0 

7.51 

7.76 

8.01 

8.26 

8.51 

8.76 

9-02 

9.27 

952 

978 

10.03 

5.0 

5.1 

7.53 

7.78 

8.03 

8.28 

8.53 

879 

904 

9.29 

954 

980 

10.05 

5.1 

5.2 

7.55 

7.80 

8.05 

8.30 

8.55 

8.8l 

906 

9.31 

9-56 

9.82 

10.07 

5.2 

5.3 

7.57 

7.82 

8.07 

8.32 

8.57 

8.83 

908 

9.33 

958 

984 

10.09 

5.3 

5.4 

7.59 

'7.84 

8.09 

8.34 

8.60 

8.85 

910 

9.36 

9-61  ' 

9.86 

10.11 

5.4 

5.5 

7.61 

7.86 

8.11 

8.36 

8.62 

88? 

912 

9.38 

963 

9.88 

10.13 

5.5 

5.6 

7.63 

7.88 

8.13 

8.39 

8.64 

8.89 

9-15 

9.40 

965 

990 

10.15 

5.6 

5.7 

7.65 

7.90 

8.15 

8.41 

8.66 

8.91 

9-17 

9.42 

967 

992 

10.17 

5.7 

5.8 

7.67 

7.92 

8.17 

8.43 

8.68 

8.94 

9-19 

9.44 

969 

994 

10.19 

5.8 

5.9 

7:69 

7.94 

8.20 

8.45 

8.70 

8.96 

921 

9.46 

971 

996 

10.22 

5.9 

6.0 

7.71 

7.96 

8.22 

8.47 

8.72 

8.98 

9-23 

9.48 

973 

9.98 

10.24 

6.0 

182  THE  ANALYSIS  OF  MILK. 

Table  X,  page  181,  based  upon  this  formula  and  taken  from 
Farrington  and  Woll,  shows  the  solids  not  fat  and  spindle 
readings  of  26  to  36.  The  spindle  readings  refer  to  the  last 
two  figures  of  the  specific  gravity  ;  for  instance,  if  the  specific 
gravity  were  1.032,  this  would  be  represented  in  the  table  by 
spindle  reading  32. 

It  is  thus  seen  that  by  adding  the  fat  and  solids  not  fat  the 
total  solids  of  the  milk  are  obtained.  In  nearly  all  cases  the 
difference  between  the  actual  determination  of  the  solids  not 
fat  and  the  figure  obtained  by  calculation  does  not  differ  mater- 
ially. The  inspector  consequently  by  merely  determining  the 
fat  and  the  gravity  will  be  in  a  position  to  judge  whether  or 
no  milk  under  examination  is  or  is  not  up  to  the  required 
standard  for  pure  milk. 

Preliminary  tests  of  milk.  It  is  often  desirable  to  make  pre- 
liminary tests  of  milk  with  reference  to  its  quality,  for  which 
there  are  to  be  obtained  several  devices.  These  are  well 
described  by  Wing  (6),  who  also  gives  a  very  interesting  sum- 
mary of  the  development  of  the  tests  for  fat  previous  to  the 
invention  of  the  BabcOck  test. 

Acidity  of  milk.  This  is  a  point  which  should  receive  more 
attention  from  the  health  officer  than  it  ordinarily  does.  Milk 
fresh  from  the  COWT  will  often  show  an  amphoteric  reaction 
but  soon  afterwards  it  will  show  an  acid  reaction  and  this  acid- 
ity will  vary  greatly,  depending  entirely  upon  how  the  milk 
has  been  handled.  The  Committee  on  Chemical  Standards  of 
the  American  Association  of  Medical  Milk  Commissions  rec- 
ommended that  the  maximum  acidity  of  milk  allowed  should 
be  0.18  c/(.  calculated  as  lactic  acid.  The  writer  considers  this 
to  be  a  very  generous  standard. 

The  acidity  of  milk  should  be  determined  at  times  but  not 
as  a  routine  procedure.  This  may  very  easily  be  done  by  the 
use  of  the  Farrington  alkaline  tablet  test  as  fully  described  in 
Farrington  and  Woll  (6).  The  test  is  very  simple  and  does 
not  require  an  expensive  outlay  for  apparatus,  but  it  must  be 
emphasized  that  only  distilled  water  or  a  clean,  non -alkaline 
soft  water  should  be  used  for  dissolving  the  tablets. 


FEDERAL  STANDARDS.  183 

A  high  acidity  indicates  bacterial  changes,  the  result  of  some 
combination  of  the  factors  of  uncleanliness,  poor  refrigeration 
and  age. 

Federal  standards.  In  connection  with  the  enforcement  of 
the  pure  food  and  drugs  act,  the  following  standards  proclaimed 
by  the  Secretary  of  Agriculture  have  been  adopted  (13). 

MIIvK  AND  ITS  PRODUCTS. 


1.  Milk  is  the  fresh,  clean,  lacteal  secretion  obtained  by  the  complete 
milking  of  one  or  more  healthy  cows,  properly  fed  and  kept,  excluding 
that  obtained  within  fifteen  days  before  and  ten  days  after  calving,  and 
contains  not  less  than  eight  and  one-half  (8.5)  per  cent  of  solids  not  fat, 
and  not  less  than  three  and  one-quarter  (3.25)  per  cent  of  milk  fat. 

2.  Blended  milk  is  milk  modified  in  its  composition  so  as  to  have  a 
definite  and  stated  percentage  of  one  or  more  of  its  constituents. 

3.  Skim  milk  is  milk  from  which  a  part  or  all  of  the  cream  has  been 
removed  and  contains  not  less  than  nine  and  one-quarter  (9.25)  per  cent 
of  milk  solids. 

4.  Pasteurized  milk  is  milk  that  has  been   heated  below  boiling  but 
sufficiently  to  kill  most  of  the  active  organisms  present  and  immediately 
cooled  to  50°  Fahr.  or  lower. 

5.  Sterilized  milk  is  milk  that  has  been  heated  at  the  temperature  of 
boiling  water  or  higher  for  a  length  of  time  sufficient  to   kill   all  organ- 
isms present. 

6.  Condensed  milk,  evaporated  milk,  is  milk  from  which  a  considera- 
ble portion  of  water   has  been  evaporated  and  contains  not  less  than 
twenty-eight  (28)  per  cent  of  milk  solids  of  which  not  less  than  twenty- 
seven  and  five-tenths  (27.5)  per  cent  is  milk  fat. 

7.  Sweetened  condensed  milk  is  milk  from  which  a  considerable  por- 
tion of  water  has  been  evaporated  and  to  which  sugar  (sucrose)  has  been 
added,  and  contains  not  less  than  twenty-eight  (28)  per  cent  of  milk  sol- 
ids, of  which  not  less  than  twenty-seven  and  five-tenths  (27.5)  per  cent 
is  milk  fat. 

8.  Condensed  skim  milk  is  skim  milk  from  which  a  considerable  por- 
tion of  water  has  been  evaporated. 

9.  Buttermilk  is  the  product  that  remains  when  butter  is  removed 
from  milk  or  cream  in  the  process  of  churning. 

10.  Goafs  milk,  ewe^s  milk,  et  cetera,   are  the  fresh,  clean,  lacteal 
secretions,,  free   from   colostrum,  obtained   by  the  complete  milking  of 
healthy  animals  other  than  cows,  properly  fed  and  kept,  and  conform  in 
name  to  the  species  of  animal  from  which  they  are  obtained. 


184  THE  ANALYSIS  OF  MILK. 

b.     CREAM. 

1.  Cream  is  that  portion  of  milk,  rich  in  milk  fat,  which  rises  to  the 
surface  of  milk  on  standing,  or  is  separated  from  it  by  centrifugal  force, 
is  fresh  and  clean  and  contains  not  less  than  eighteen  (18)  per  cent  of 
milk  fat. 

2.  Evaporated  cream,  clotted  cream,  is  cream  from  which  a  consider- 
able portion  of  water  has  been  evaporated. 

State  standards.  In  drafting  local  dairy  ordinances  it  is 
desirable  to  have  the  standards  conform  to  the  requirements  of 
the  state  law.  In  California,  the  courts  have  ruled  that  the 
city  ordinances  can  conflict  with  those  of  the  state  to  the  ex- 
tent of  raising  the  local  standard  above  that  adopted  by  the 
state. 

Collection  of  samples.  One  of  the  most  important  and 
weighty  considerations  is  the  proper  collection  of  milk  samples. 
This  necessitates  the  employment  of  trained  inspectors.  It 
would  appear  from  the  experience  of  the  writer  that  this  point 
'is  not  ordinarily  kept  in  mind  when  officers  are  appointed. 
The  inspector  should  either  be  a  dairy-school  graduate  well 
recommended  or  should  receive  the  necessary  training  in  the 
laboratory  with  which  he  is  to  be  associated. 

Samples  from  milk  cans,  whether  from  store  or  wagon,  should 
be  collected  with  care  in  the  matter  of  mixing  as  pointed  out 
on  page  177.  An  additional  precaution  regarding  the  use  of 
the  sampling  tube  might  not  be  out  of  place.  The  tube  should 
be  thoroughly  rinsed  after  each  sample  has  been  taken  in  order 
to  preclude  the  possibility  of  contaminating  one  sample  with 
traces  of  a  preservative  that  might  have  been  in  the  previous 
one. 

One  of  the  most  convenient  receptacles  for  collecting  milk  is 
a  wide-mouthed  eight-ounce  bottle  with  a  well-fitted  cork. 
Duplicate  samples  'should  be  collected  in  order  that  the  party 
from  whom  the  sample  is  taken  may  retain  one  for  analysis  if 
he  so  desires.  Dairy  ordinances  should  require  that  this  be 
done. 

In  the  case  of  bottled  milk  also  it  would  appear  to  be  desir- 
able to  collect  duplicate  samples.  This  may  readily  be  done 
by  the  inspector  carrying  in  his  outfit  a  clean  quart  bottle  for 


RKFKKKNCES.  185 

mixing  samples.  He  would  thus  be  enabled  to  thoroughly 
mix  the  contents  of  a  sample  of  bottled  milk  in  the  presence 
of  the  vender  and  to  give  half  to  the  vender  as  a  duplicate. 
If  this  method  is  followed  there  can  be  no  dispute  as  to  the 
authenticity  of  the  samples  collected. 

It  is  highly  essential  that  the  inspector  be  provided  with  a 
book- of  numbered  blank  forms  containing  also  small  slips  bear- 
ing duplicate  numbers.  One  of  these  slips  should  go  on  each 
sample  for  purposes  of  identification.  The  blanks  should  call 
for  information  covering  the  essential  facts  regarding  the  source 
of  the  sample  and  should  be  in  duplicate.  The  inspector 
retains  the  original  in  his  book  and  the  duplicate  goes  with 
the  sample  to  the  chemist. 

All  samples  must  be  duly  sealed  in  the  presence  of  the  vender. 
This  may  be  done  by  the  use  of  gummed  paper  strips  printed 
with  an  appropriate  legend  and  pasted  over  the  cork.  The 
seal  bears  a  printed  number  corresponding  to  that  of  the  blank 
form.  Sealing  wax  impressed  with  a  distinctive  device  may 
also  be  used  for  the  purpose  of  sealing  the  sample.  In  this 
case  the  cork  must  be  flush  with  the  top  of  the  neck  of  the 
bottle,  for  the  wax  is  smeared  over  both. 


REFERENCES. 

1.  AIKMAN.     Milk,  its  nature  and  composition.     London:  Adam  and 
Charles  Black,  1899. 

2.  ALLEN.     Commercial  organic  analysis.     Vol.  IV.     Philadelphia  : 
P.  Blakiston's  Son  &  Co.,  1898. 

3.  ATWATRR  and  BRYANT.     Chemical  composition  of  American  food 
materials.      Bui.  No.  28  (revised},   Office  of  E.rp.   Sta.,    L\  S.  Dept. 
Agr.,  Washington,  D.  C.,   1906. 

4.  BL.YTH.      Foods,    their  composition  and  analysis.      London:    Ch. 
Griffin  &  Co.,  Ltd.,  1903. 

'5.     FARRINGTON  and  Wot,!,.     Testing  milk  and  its  products.     Madi- 
son, Wis.:  Mendota  Book  Co.,  1908. 

6.     FARRINGTON.      Variations  in  milk.       /////.  No.  24,    I'uiv.of  III. 
Agr.  Exp.  Sta.,  Urbana,  111.,  1893. 


186  THE  ANALYSIS  OF  MILK. 

7.  HOLM.     A  new  method  for  preventing  char  in  the  Babcock  centrif- 
ugal determination   of   fat   in  milk   and  milk  products.        Atner.   l^ood 
Jonr.,  Vol.  II.  1907,  No.  7.   p.  28. 

8.  KASTLE   and   ROBERTS.      The  chemistry  of   milk.      J>nl.  Xo.  41 ', 
Hyg.  Lab.,  ('.  S.  l^nb.  Health  and  Mar.  Hosp.  Sen*., Washington.  D.  C., 
1908,  p.  309. 

9.  LANCAYORTHY.     Milk  as  food.     Faniirrs'  J'>nl.  Xo.  7X,  (  '.  S.  Dept. 
Agr.,  Washington,  D.  C.,  1904. 

10.  LEACH.     Food  inspection  and  analysis.     New  York  :  John  Wiley 
&  Sons,  1906. 

11.  RICHMOND.     Dairy  chemistry.      London:   Ch.  Griffin  &  Co.,  Ltd. 

12.  RICHMOND.      The   laboratory  lx>ok  of  dairy  analysis.      London  : 
Ch.  Griffin  &  Co.,  Ltd.,  1899. 

13.  SECRETARY  OF  AGRICULTURE.     Standards  of  purity  for  food  pro- 
ducts.     Cir.  No.  19,  Office  of  the  Secretary,    U.  S.  Dept.  A  or.,    Wash- 
ington, D.  C.,  1906. 

14.  VAN  SivYKE.      Modern   methods  of  testing  milk   and  milk   pro- 
ducts.    New  York:  Orange  Judd  Co. ,   1906. 

15.  WEBSTER.      The  fat  testing  of  cream  by    the  Babcock   method. 
Hill.  Xo.  58,  Bur.  Anini.  Ind.,  ('.  S.  Dept.  Agr.,  Washington,  D.  C.. 
1902. 

16.  WILEY  (EDITOR).     Official  and  provisional  methods  of  analysis, 
Association  of  Official  Agricultural  Chemists.      />'///.  Xo.  1<>7  (revised), 
r>nr.  of  Cheui.,  ( '.  S.  Dept.  Agr.,  Washington,  D.  C.,  1908. 

17.  WING.     Milk  and  its  products.     New  York:  The  Macmillan  Co., 
1909. 


CHAPTER  XI. 


ADULTERATION  OF  MILK. 


Introduction.  That  milk  is  easily  contaminated  and  subject 
to  deleterious  changes,  was  well  known  in  ancient  times.  This 
is  proved  by  a  reference  to  the  Talmudic  Laws,  where  the  fol- 
lowing statement  is  found  :  ' '  Milk  is  one  of  the  beverages  that 
makes  the  articles  of  food  liable  to  receive  impurities."  (3) 

It  is  true  that  chemical  preservatives  were  not  known  at  that 
time  and  consequently  were  not  used.  Such  materials,  how- 
ever, have  been  used  for  many  years  in  milk  intended  for 

human  consumption  and  the  practice  prevails  to  some  extent 

\  . 
at  the  present  time. 

It  may  be  said  that  perhaps  few  questions  concerning  the 
public  health  have  provoked  more  discussion  or  been  produc- 
tive of  more  experiments  and  investigations  than  that  of  the 
use  of  preservatives  in  foods  intended  for  human  consumption. 
It  is  of  more  than  passing  interest,  and  certainly  a  matter  of 
congratulation, -to  be  able  to  say  that  the  greater  the  advance  of 
science,  the  greater  and  more  powerful  is  the  ammunition 
brought  forward  to  fight,  and  successfully  too,  the  advocates 
of  the  use  of  deleterious  materials  in  our  food  products.  These 
substances,  as  is  well  known,  are  added  in  many  cases  for  the 
purpose  either  of  enhancing  the  value  of  poor  products  or 
preventing  or  arresting  the  decay  of  an  already  unwholesome 
food . 

The  literature  abounds  in  records  of  investigations  of  the 
influence  of  preservatives  on  the  food  value  of  milk.  For  a 
very  complete  bibliography  of  this  subject,  the  reader  is  re- 
ferred to  Kastle  and  Roberts  (4). 

Much  has  been  written  on  both  sides  of  this  all-important 
question.  If  proper  care  is  exercised  in  the  .handling  of  milk 


188  ADULTERATION  OF  MILK. 

intended  for  human  consumption,  there  is  no  necessity  for 
the  use  of  preservatives  to  insure  its  keeping  fresh.  This  is 
particularly  to  be  emphasized  in  the  care  of  milk  to  be  fed  to 
infants  and  invalids. 

While  there  is  much  evidence  in  favor  of  the  use  of  some  of 
the  preservatives  for  milk,  such  as  boric  acid  or  borax,  formal- 
dehyde, hydrogen  peroxide,  etc.,  yet  most  of  this  evidence  is 
the  result  of  artificial  digestion  experiments.  It  is  conceded 
that  such  investigations  are  of  great  scientific  value  but  too 
much  importance  must  not  be  attributed  to  them.  There  are 
many  conditions  which  obtain  in  the  natural  process  of  diges- 
tion which  cannot  be  duplicated  under  artificial  conditions. 
A  notable  instance  of  the  necessity  of  conducting  both  the  arti- 
ficial and  natural  digestion  experiments  before  drawing  any 
final  conclusions  is  recorded  by  Wiley  (6)  in  his  report  on  the 
influence  of  salicylic  acid  and  salicylates  on  digestion  and 
health. 

Wiley  states  in  his  conclusions  : 

' '  The  data  show  very  clearly  that  salicylic  acid  and  salicylates  appear 
to  exert  an  exciting  influence  upon  the  activities  which  take  place  in  the 
alimentary  canal,  stimulating  the  organs  to  greater  effort,  and  this  stim- 
ulation leads  at  first  to  increased  digestion  and  absorption  of  the  foods 
which  are  introduced  into  the  stomach.  In  the  light  of  the  data  which 
are  exhibited,  salicylic  acid  may  be  said  to  increase  the  solubility  and 
absorption  of  the  food  in  the  alimentary  canal,  so  that  large  parts  of  the 
nutrients  taken  into  the  stomach  actually  enter  the  circulation. 

"The  data  which  show  the  effects  just  noted  also  indicate  that  the 
general  effect  upon  the  system  is  depressing,  in  that  the  tissues  are  bro- 
ken down  more  rapidly  than  they  are  built  up,  and  thus  the  normal 
metabolic  processes  are  interfered  with  in  a  harmful  way.  The  admin- 
istration of  the  salicylic  acid  is  attended  by  a  gradual  decrease  in  the 
weight  of  the  subjects,  altho  the  quantity  of  food  elements  administered 
during  the  preservative  and  after  periods  is  slightly  increased,  which 
fact,  together  with  a  greater  degree  of  absorption  of  the  food  elements, 
should  have  resulted  in  a  slight  increase  in  weight.  This  increase  in 
weight,  however,  does  not  occur,  and  the  disturbing  influences  of  the 
salicylic  acid  upon  metabolism,  altho  not  very  great,  are  specifically 
demonstrated." 

The  natural  inference  from  an  artificial  digestion  experiment, 
along  the  lines  indicated,  would  be  that  salicylic  acid  is  a 


INTRODUCTION.  189 

help  rather  than  a  hindrance  to  digestion  of  proteids,  whereas 
the  inference  from  the  natural  digestion  experiment  is  just  the 
reverse. 

It  is  admitted,  of  cour.se,  that  it  is  almost  impossible  to  con- 
duct metabolism  experiments  with  infants  as  subjects,  and  they 
are  the  very  class  most  concerned.  Among  the  many  experi- 
ments carried  on  with  very  young  animals  are  those  of  Annett 
(l).  The  subject  of  his  experiments  were  kittens  three  weeks 
of  age.  The  milk  fed  was  treated  with  boric  acid.  The  amounts 
for  the  two  experiments  were  respectively  40  and  80  grains  of 
boric  acid  per  gallon  of  milk.  At  the  end  of  the  four  weeks,  all 
kittens  fed  on. the  adulterated  milk  were  dead,  while  the  con- 
trol lot,  which  were  fed  pure  milk,  were  alive  and  healthy. 

This  series  of  experiments  was  followed  by  a  similar  one, 
the  milk,  however,  being  treated  with  formaldehyde  in  place  of 
boric  acid.  The  results  of  the  latter  experiments  were  not  so 
conclusive  as  were  those  obtained  from  the  boric  acid  test.  At 
the  same  time,  the  data  obtained  are  of  more  than  'passing 
interest.  In  the  first  experiment,  the  milk  contained  7  parts 
formaldehyde  to  50,000  parts  milk.  In  the  second  experiment, 
the  proportion  of  formaldehyde  was  just  doubled,  or  1  to  2.5,000. 
In  the  third  experiment,  the  proportion  of  formaldehyde  was 
again  doubled,  or  1  part  to  12,500.  It  was  noted  that  the  gain 
in  weight  in  all  three  experiments  by  the  control  kittens  receiv- 
ing only  pure  milk  was  far  ahead  of  the  gain  of  those  receiving 
the  adulterated  article.  This  is  particularly  emphasized  in  the 
third  experiment.  These  results  are  at  variance  with  many  of 
the  findings  recorded  for  artificial  digestion  experiments  but  as 
they  have  stood  the  test  of  criticism  and  investigation  they 
must  be  accorded  serious  consideration. 

It  is  perhaps  gratifying  to  know  that  Annett 's  views  on  this 
subject  are  ably  supported  by  the  reports  of  Wiley  (6)  on  the 
influence  of  food  preservatives  and  artificial  colors  on  digestion 
and  health.  The  subjects  of  Wiley's  experiments  were  all 
healthy  young  men,  and  it  was  clearly  shown  that  the  preserv- 
atives studied,  viz.,  borax,  salicylic  acid,  sulphites  and  benzoic 
acid,  and  formaldehyde,  were  deleterious  substances  and  pro- 
duced digestive  disturbances. 


190  ADULTERATION  OF  MILK. 

In  view  of  the  contradictory  mass  of  evidence  which  is  at 
hand  as  shown  by  Kastle  and  Roberts  (4),  it  would  appear 
that  laws  forbidding  the  use  of  preservatives  in  milk  intended 
for  human  consumption  are  certainly  to  be  recommended  as 
safeguarding  the  public  health.  The  strong,  healthy  stomach 
may  and  can  withstand  strains  to  which  the  delicate  digestive 
organs  of  an  infant  or  invalid  would  succumb. 

Tests  for  preservatives.  A  complete  examination  of  a  sample 
of  milk  for  preservatives  would  include  tests  for  boracic  acid 
and  its  compounds,  formaldehyde,  fluorids,  benzoic  acid  and 
its  compounds,  salicylic  acid  and  salicylates,  peroxide  of  hydro- 
gen, etc.  Such  thorough  analytical  work  can.  be  conducted 
only  in  a  well-equipped  laboratory.  It  is  assumed  that  the 
man  in  charge  of  the  work  is  an  expert  and  has  at  his  disposal 
the  necessary  standard  works  describing  the  tests.  For  this 
reason  it  is  not  considered  necessary  to  reprint  the  methods  for 
making  such  determinations.  The  preservatives  most  com- 
monly used  are  borax  and  formaldehyde.  It  is  fortunate  that 
there  are  simple  and  reliable  tests  for  these  two. 

Borax.  A  preliminary  test  may  be  made  for  boric  acid  and 
borates  by  immersing  a  strip  of  turmeric  paper  in  about  100  cc. 
of  milk  to  which  about  7  cc.  of  concentrated  hydrochloric  acid 
has  been  added.  If  boric  acid  or  borax  is  present,  the  paper 
on  drying  will  acquire  a  peculiar  red  color  which  is  changed  by 
ammonium  hydrate  to  a  dark  blue-green  but  is  restored  by  acid. 
The  above  mentioned  reagents  can  easily  be  obtained  at  a  drug 
store.  A  positive  reaction  would  indicate  the  presence  of 
borax  but  a  negative  reaction  might  not  in  all  cases  mean  that 
the  material  does  not  contain  borax  but  would  require  further 
examination  where  better  laboratory  facilities  could  be  ob- 
tained. 

Formaldehyde.  This  is  without  doubt  the  best  preservative 
of  milk.  So  efficacious  is  this  material  that  there  are  many 
compounds  to  be  found  on  the  market  under  various  names, 
such  as  "  callerine,"  "  freezine,"  etc.  These  different  prepar- 
ations are  weak  solutions  of  formaldehyde,  ranging  from  about 
3%  to  7%  in  strength. 


\V. \TKKING  OF  MII.K.  191 

There  are  two  different  methods  which  are  easily  carried 
out, — those  of  Hehner  and  Leach. 

Hchncr 's  test  for  formaldehyde  : 

"To  10  cc.  of  milk  in  a  wide  test  tube  add  about  half  the  volume  of 
concentrated  commercial  sulphuric  acid,  pouring-  the  acid  carefully  down 
the  side  of  the  tube  so  that  it  forms  a  layer  at  the  bottom,  without  mix- 
ing with  the  milk.  A  violet  /.one  at  the  junction  of  the  two  liquids  indi- 
cates formaldehyde.  The  coloration  produced  depends  on  the  presence 
of  a  very  small  amount  of  iron.  For  this  reason  the  ordinary  commercial 
acid  used  in  the  Babcock  test  answers  well  for  this  test.  However,  if  an 
excess  of  formaldehyde  is  present  in  the  milk,  this  test  wTill  not  indicate 
the  presence  of  the  preservative." 

Leach' s  test  for  formaldehyde  : 

"Commercial  hydrochloric  acid  (specific  gravity  1.2)  containing  2  cc. 
of  10  %  ferric  chloride  per  liter  is  used  as  a  reagent.  Add  10  cc.  of  the 
acid  reagent  to  an  equal  volume  of  milk  in  a  porcelain  casserole,  and 
heat  slowly  over  the  free  flame  nearly  to  boiling,  holding  the  casserole 
by  the  handle,  and  giving  it  a  rotary  motion  while  heating  to  break  up 
the  curd.  The  presence  of  formaldehyde  is  indicated  by  a  violet  color- 
ation, varying  in  depth  with  the  amount  present.  In  the  absence  of 
formaldehyde,  the  solution  slowly  turns  brown.  By  this  test  1  part  of 
formaldehyde  in  250,000  parts  of  milk  is  readily  detected  before  the  milk 
sours.  After  souring,  the  limit  of  delicacy  proves  to  be  about  1  part  in 
50,000." 

The  porcelain  casserole  can  be  obtained  at  any  chemical  sup- 
ply house  and  the  solution  as  indicated  can  very  easily  be  made 
up  by  any  druggist.  In  place  of  the  gas  flame,  an  alcohol 
lamp  may  be  used.  A  word  of  caution  must  be  mentioned 
with  reference  to  this  test,  because  it  is  so  delicate.  In  at  least 
one  instance  the  use  of  absorbent  cotton  in  a  strainer  at  a  good 
dairy  resulted  in  the  finding  of  formaldehyde  in  the  milk. 
Investigation  showed  that  the  cotton  had  been  sterilized  with 
formaldehyde  by  the  manufacturers.  The  use  of  formaldehyde 
in  the  tubes  of  milking  machines  offers  like  possibilities  for  the 
contamination  of  milk  by  this  chemical. 

Watering  of  milk.  One  of  the  more  common  sophistications 
of  milk  is  the  addition  of  water.  Such  a  practice  is  not  only  a 
pecuniary  fraud  but  it  both  lowers  the  nutritive  value  and 
may  prove  at  times  to  be  a  menace  to  health,  as  discussed  in 
Chapters  III  and  V. 


192  ADULTERATION  OF  MII«K. 

The  effect  of  the  added  water  is  to  lower  the  specific  gravity 
and  also  the  percentage  of  all  the  ingredients. 

The  determination  of  fat  alone  is  not  sufficient  to  indicate 
in  all  cases  whether  or  not  water  has  been  added  to  milk. 
This  could  be  illustrated  by  many  instances,  notably  in  the 
case  of  Jersey  milk  containing  6%  fat.  Such  milk  could  be 
diluted  with  50%  water  and  at  the  same  time  yield  4f/f  fat. 
Judged  by  the  fat  content  alone,  the  watered  milk  would  be 
considered  of  high  quality,  while  the  nutritive  value  would  be 
only  two-thirds  of  the  normal.  Serious  mistakes  have  been 
made  by  modifying  for  infant  feeding  just  such  watered  milk, 
upon  the  assumption  that  it  was  a  normal  milk  containing  4% 
fat. 

The  determination  of  the  specific  gravity  when  the  only 
sophistication  of  the  milk  is  that  of  added  water,  is  of  great 
value.  A  low  specific  gravity,  that  is,  below  1.028,  with  a  low 
fat  content,  is  a  very  sure  indication  of  added  water.  When 
an  inspector  finds  such  conditions  the  sample  should  be  exam- 
ined by  the  immersion  refractometer.  Full  directions  for 
using  this  instrument  are  to  be  found  in  Leach  (5).  A  read- 
ing below  39  indicates  added  water,  between  39  and  40  the 
sample  is  to  be  regarded  as  suspicious.  If  it  is  not  possible  to 
have  access  to  a  refractometer  a  determination  of  milk  sugar 
will  be  very  helpful.  A  low  sugar  content,  that  is,  below 
4%,  in  connection  with  a  low  gravity  and  fat,  indicates  added 
water. 

Skimming.  The  removal  of  the  cream  is  to  be  considered 
an  adulteration  in  that  the  consumer  is  deceived  and  misled. 
Evidence  regarding  whether  or  not  a  given  sample  of  milk  Jias 
been  skimmed  is  mainly  gathered  from  results  of  the  test  for 
fat.  The  only  cases  where  this  test  is  not  reliable  are  to  be 
found  in  the  rich  milks  of  the  Channel  Island  breeds,  which 
can  be  skimmed  and  still  indicate  a  fat  per  cent,  above  many 
of  the  legal  standards. 

Carbonate  of  soda.  This  and  the  bicarbonate  are  occasion- 
ally used  to  lessen  the  acidity  of  old  milk.  The  addition  of 
these  compounds  to  milk  is  to  be  considered  in  that  they  are 
added  to  conpeal  inferiority.  For  detection,  see  Leach  (5). 


COLORING  MATTER.  193 

Thickening  agents  for  cream.  Gelatin  is  added  to  cream  for 
the  purpose  of  increasing  viscosity  and  giving  the  appearance 
of  greater  richness  than  is  really  the  case.  For  detection,  see 
Leach  (5). 

Sucrate  of  lime  (viscogen)  is  sometimes  used  in  order  to 
make  pasteurized  cream  whip.  It  is  a  harmless  adulteration 
and  permissible  when  the  product  is  so  labeled. 

Heated  milk.  Storch  has  devised  a  test  that  will  indicate 
whether  milk,  cream  or  other  dairy  products  have  been  heated 
to  178°  F.  (80°C.).  It  is  carried  out  as  follows  :  A  teaspoon- 
ful  of  milk  is  poured  into  a  test  tube  and  one  drop  of  a  weak 
solution  of  peroxide  of  hydrogen  (2%)  and  two  drops  of  a  2% 
solution  of  paraphenyldiamin  are  added.  The  mixture  is  then 
shaken.  If  a  dark  violet  color  appears  at  once,  the  milk  has 
not  been  heated,  or  at  any  rate,  not  above  175°  F. 

Coloring  matter.  The  chief  object  of  adding  coloring  matter 
to  milk  is  for  the  purpose  of  concealing  either  skimming  or 
watering.  Two  classes  of  compounds  are  used,  vegetable  and 
coal-tar  colors.  Some  of  the  latter  are  harmless,  as  naphthol 
yellow  S  or  Orange  I,  as  declared  in  the  U.  S.  Department  of 
Agriculture,  Food  Inspection  Decision  76.  Only  a  very  small 
amount  of  coloring  matter  is  used  and  the  effect  is  generally 
harmless  ;  but  such  additions  are  in  violation  of  the  law  in 
that  they  tend  to  mislead  and  deceive  the  consumer.  The 
detection  of  added  coloring  matter  in  milk  cannot  very  well  be 
undertaken  away  from  a  chemical  laboratory.  Full  and  com- 
plete directions  for  the  testing  of  milk  for  the  presence  of 
added  coloring  matter  will  be  found  in  Bulletin  No.  107  (7). 

If  there  is  any  suspicion  that  a  milk  has  been  adulterated 
with  coloring  matter,  it  should  be  allowed  to  stand  undis- 
turbed for  several  hours  in  a  glass  vessel.  If  then  the  sample 
exhibits  different  zones  of  color,  it  may  safely  be  said  that  the 
milk  contains  no  added  coloring  matter.  The  different  colors 
should  be  the  yellow  of  the  cream,  which  overlies  the  stratum 
of  a  mixture  of  milk  and  cream  of  a  lighter  color,  under  which 
is  the  bluish  layer  of  skimmed  milk.  If,  on  the  other  hand, 
the  color  is  more  or  less  uniform  throughout  the  sample,  it 
should  be  further  examined  for  confirmation. 


194  ADULTERATION  OF  MILK. 

REFERENCES. 

1.  ANNETT.     Boric  acid  and. formalin  as  milk  preservatives.     I^ancet, 
Vol.  II,  1899,  p.  1282. 

2.  DOANK  and  PRICK.      Influence  of  preservatives  on  food  value  of 
milk.     Bui.  Xo.  86,  Maryland  Agr.  Exp.  Sta.,  College  Park,  Md.,  1902. 

3.  Jewish  Encyclopedia,  Vol.  VIII,  1904,  p.  591. 

4.  KASTLE  and  ROBERTS.       The  chemistry  of  milk.       Bui.  Xo.   //. 
Hyg.  Lab.,    U.  S.   Pub.   Health  and  Mar.  Hasp.   Sen1.,   Washington, 
D.  C.,  1908,  p.  309. 

5.  IvEACH.     Food  inspection  and  analysis.     New  York  :  John  Wiley 
&  Sons,  1906. 

6.  WilyEY.      Influence  of  food  preservatives  and  artificial  colors  on 
digestion  and  health.       liul.  Aro.  84,  Bur.   Chon.,    l\  S.  Dcpt.  Agr., 
Washington,  D.  C.,  Part  I,  1904;  Part  II,  1906. 

7.  WiivEY  (EDITOR).     Official  and  provisional  methods  of  analysis, 
Association  of  Official  Agricultural  Chemists.     Bui.  Xo.  107  (revised'}, 
Bur.  Chem.,  U.  S.  Dept.  Agr.,  Washington,  D.  C.,  1908. 


APPENDIX  A. 

DAIRY  ORDIXANCK  OF  BKRKKLKY, 


ORDINANCE  No.  495 — A. 

Providing  for  the  Inspection  of  Milk,  Dairies  and  Dairy  Herds,  and  Regu- 
lating the  Sale-  and  Disposition  of  Milk  in  the  Town  of  Berkeley,  and 
Providing  a  Penalty  for  the  Violation  of  Said  Ordinance. 


Be  it  ordained  by  the  Board  of  Trustees  of  the  Town  of  Berkeley,  as 
follows  : 

Sec.  1.  From  and  after  October  10,  1907,  no  person  shall  offer  or  ex- 
pose for  sale,  or  sell  or  deliver  for  sale  or  consumption  within  the  Town 
of  Berkeley  any  milk  or  cream,  without  first  obtaining  and  having  a 
permit  therefor  from  the  Health  Officer  in  accordance  with  the  condi- 
tions in  this  ordinance  hereinafter  provided. 

Sec.  2.  Any  person  desiring  a  permit  to  engage  in  the  sale  or  disposi- 
tion of  milk,  as  provided  in  Section  1  hereof,  shall  first  make  application 
therefor,  to  the  Health  Officer  of  the  Town  of  Berkeley  by  filing  with 
the  Health  Officer  an  application  in  writing  therefor,  which  said  appli- 
cation shall  set  forth  with  reasonable  exactness  the  name  and  place  of 
residence  of  the  applicant,  the  exact  location  or  place  from  which  the 
applicant  obtains  or  is  to  obtain  his  milk,  and  if  the  applicant  is  no4L a 
producer  of  milk,  then  the  name  of  the  person  or  persons  from  whom  he- 
obtains  or  is  to  obtain  his  milk  for  sale  or  distribution,  and  if  said  appli- 
cant is  a  producer  of  milk,  the  number  of  cows  in  his  dairy 'herd,  or  if 
he  is  not  a  producer'  of  milk,  the  number  of  cows  in  the  dairy  herd  of 
the  person  or  persons  from  whom  he  obtains  or  is  to  obtain  his  milk  ; 
there  shall  also  be  filed  with  the  Health  Officer  the  veterinary  surgeon's 
certificate  required  by  Section  6  of  this  ordinance  concurrently  with  the 
application  heretofore  mentioned  ;  and  said  application  shall  further  set 
forth  the  manner  in  which  the  applicant  intends  to  dispose  of  his  milk 
when  granted  such  permit,  according  to  the  provisions  of  this  ordinance, 
and  shall  be  signed  by  the  applicant,  and  when  received  by  the  Health 
Officer  shall  be  placed  on  file  and  the  name  of  the  applicant  shall  In- 
registered  in  a  took  of  registration  kept  for  such  purpose. 

Sec.  3.  Any  such  applicant,  or  any  person  from  whom  such  appli- 
cant obtains,  or  is  to  obtain  his  milk,  shall  permit  the  Health  Officer  of 
the  Town  of  Berkeley,  his  assistants  and  deputies,  to  inspect  the  dairy 
and  the  dairy  herds  of  such  applicant,  or  the  dairy  and  dairy  herd  of 
the  person,  or  persons,  from  whom  the  applicant  obtains,  or  is  to  obtain 


196  APPENDICES. 

his  milk,  by  physical  examination  and  the  tuberculin  test  of  the  cows 
for  the  purpose  of  determining  the  presence  or  absence  of  tuberculosis, 
together  with  all  appliances  and  milk  vessels  used  therein,  and  any 
refusal  upon  the  part  of  such  applicant,  or  upon  the  part  of  the  person 
or  persons  from  whom  such  applicant  obtains  or  is  to  obtain  his  milk,  to 
permit  the  inspection  above  referred  to  shall  be  deemed  a  sufficient 
ground  upon  which  the  Health  Officer  may  refuse  to  issue  the  permit 
applied  for,  and  for  such  cause  may  revoke  the  same  after  its  issuance. 

Sec.  4.  It  shall  thereupon  be  the  duty  of  the  Health  Officer  to  issue 
a  permit  or  permits  to  sell  or  distribute  milk  within  the  corporate  limits 
of  the  Town  of  Berkeley  to  each  applicant  who  has  complied  with  the 
requirements  of  this  ordinance,  which  said  permit  shall  be  numbered 
and  signed  by  the  Health  Officer,  and  a  record  thereof  shall  be  kept  in 
the  book  of  registration  provided  for  in  Section  2  hereof,  and  said  permit 
shall  be  valid  and  effective  for  the  period  of  one  year  from  and  after  the 
date  of  its  issuance,  unless  sooner  revoked  by  said  Health  Officer  for 
violation  of  any  of  the  provisions  of  this  ordinance. 

Sec.  5.  Bach  person  granted  a  permit  under  the  provisions  of  this 
ordinance  shall  cause  his  name  and  his  place  of  business  and  the  num- 
ber of  his  permit  to  be  legibly  placed  in  a  conspicuous  place  on  the  outer 
side  of  all  carriages,  wagons  or  other  vehicles  used  by  him  in  the  sale 
or  distribution  of  milk  within  the  corporate  limits  of  the  Town  of  Berke- 
ley, and  all  persons  who  sell  milk  from  stores  or  shops  shall  keep  their 
permit  constantly  posted  in  a  conspicuous  place  upon  the  wall  of  the 
room  within  wrhich  such  sale  of  milk  is  prosecuted  or  carried  on. 

Sec.  6.  No  person  shall  bring  into  the  Town  of  Berkeley  for  sale, 
either  by  wragon,  cart,  train  or  any  other  kind  of  vehicle,  or  keep,  have 
or  offer  for  sale,  or  sell  in  said  towyn,  any  milk  or  cream  contained  in. 
cans,  bottles  or  packages  unless  such  cans,  bottles  and  packages  contain- 
ing such  milk  or  cream  for  sale  shall  be  marked  writh  a  legible  stamp, 
tag  or  impression  bearing  the  name  of  the  owner  of  the  cows  from  which 
such  milk  was  drawn,  giving  his  place  of  business,  including  name  of 
city,  street  and  number,  and  unless  the  owrner  or  owners  of  such  cows 
shall  first  file  in  the  office  of  the  Health  Officer  a  certificate  of  a  duly 
licensed  veterinary  surgeon,  stating  that  such  cows  have  been  subjected 
to  a  physical  examination  and  the  tuberculin  test  for  the  purpose  of 
detecting  the  presence  or  absence  of  tuberculosis,  and  shall  state  the 
results  of  his  examination  of  them  writh  reference  to  the  existence  of 
other  infectious  or  contagious  diseases.  Such  certificate  shall  give  a 
number  which  has  been  permanently  attached  to  each  cow  and  shall 
state  the  date,  the  place  of  examination,  the  temperature  of  the  cow  or 
cows  at  intervals  of  three  hours  for  twyelve  hours  before  the  subcutane- 
ous injection  of  the  tuberculin,  the  temperature  at  the  tenth  hour  after 
the  injection  of  the  tuberculin,  and  every  three  hours  after  the  aforesaid 
tenth  hour,  for  twelve  hours,  or  until  the  reaction  is  completed.  The 


APPENDIX   A.  197 

said  certificate  shall  further  contain  the  conclusions  of  the  veterinary 
surgeon  touching  the  presence  or  absence  of  tuberculosis  in  the  animal 
or  animals  examined,  drawn  from  the  data  afforded  by  the  physical 
examination  and  the  tuberculin  test.  Said  certificate  shall  be  accom- 
panied by  a  description  of  the  animal  or  animals  tested,  sufficiently 
accurate  to  serve  for  purposes  of  identification. 

Sec.  7.  No  milk  which  is  watered,  adulterated,  reduced  or  changed  in 
any  respect  by  the  addition  of  water  or  other  substance  or  by  the 
removal  of  cream,  or  milk  which  has  been  drawn  from  cows  suffering 
from  tuberculosis  or  any  other  contagious  disease,  or  milk  which  has 
been  drawn  from  cows  which  have  not  been  inspected  by  a  duly  licensed 
veterinary  surgeon  and  tested  by  physical  examination  and  the  tubercu- 
lin test  for  the  purpose  of  detecting  the  presence  or  absence  of  tubercu- 
losis, shall  be  brought  into  the  Town  of  Berkeley,  or  held,  kept,  sold  or 
offered  for  sale  at  any  place  in  said  town,  nor  shall  any  person,  persons 
or  corporation  keep,  have,  sell  or  offer  for  sale  any  such  milk  in  said 
Town  of  Berkeley,  except  that  milk  from  which  any  part  of  the  cream 
has  been  removed  may  be  sold  in  the  manner  hereinafter  provided. 

The  term  "adulterated  milk,"  as  used  in  this  ordinance,  means: 

First — Milk  containing  more  than  eighty-eight  per  centum  of  water 
fluids. 

Second — Milk  containing  less  than  twelve  (12)  per  centum  of  milk 
solids. 

Third — Milk  containing  less  than  three  (3)  per  centum  of  fats. 

Fourth — Milk  drawn  from  animals  within  fifteen  (15)  days  before  or 
five  (5)  days  after  parturition. 

Fifth — Milk  drawn  from  animals  fed  on  any  .substance  in  a  state  of 
fermentation  or  putrification  or  on  any  unwholesome  food. 

Sixth — Milk  drawn  from  cows  kept  in  a  crowded  or  unhealthy  condi- 
tion, or  from  cows  suffering  with  tuberculosis  or  any  other  contagious 
disease. 

Seventh— Milk  from  wrhich  any  part  of  the  cream  has  been  removed. 

Eighth — Milk  w7hich  has  been  diluted  with  water  or  any  other  fluid, 
or  to  which  has  been  added,  or  into  which  has  been  introduced,  any  for- 
eign substance  whatever. 

Sec.  8.  The  Health  Officer  is  hereby  authorized  to  provide  metal  ear 
tags  each  marked  with  the  words,  "  Berkeley  Board  of  Health,"  and  a 
serial  number,  and  also  to  provide  printed  blanks,  and  is  authorized  to 
distribute  them  to  any  duly  licensed  veterinary  surgeon  who  may  apply 
for  them  for  use  in  compliance  with  the  requirements  of  Section  6  of 
this  ordinance. 

Sec.  9.  Notwithstanding  the  provisions  of  Section  7  of  this  ordinance, 
milk  from  which  the  cream  has  been  removed,  if  such  milk  is  otherwise 
wholesome  and  unadulterated,  may  be  sold  as  skimmed  milk  by  dealers 
having  the  permit  provided  for  by  this  ordinance,  but  only  from  vessels 


198  APPENDICES. 

legibly  marked,  in  addition  to  the  stamp,  tag,  or  impression  provided 
for  in  Section  6  of  this  ordinance,  with  the  words  "Skimmed  Milk"  in 
plain  black  letters  upon  a  light  background,  and  each  letter  being  at 
least  one  inch  high  and  one-half  inch  wide,  the  said  words  being  placed 
in  a  conspicuous  place  on  the  top  or  side  of  such  vessel. 

Sec.  10.  Any  adulterated  milk  which  has  been  brought  into  the  Town 
of  Berkeley,  or  is  held  and  offered  for  sale  in  said  town,  excepting 
skimmed  milk  when  offered  for  sale  as  provided  in  this  ordinance,  may 
be  seized  and  destroyed  by  an  inspector  or  other  officer  of  the  Board  of 
Health  of  said  town  authorized  to  inspect  the  same. 

Sec.  11.  No  cream  which  is  adulterated,  or  that  shall  contain  less 
than  twenty  (20)  per  centum  of  fat,  shall  be  brought  into  the  Town  of 
Berkeley,  or  held,  kept,  sold  or  offered  for  sale  in  said  town,  nor  shall 
any  one  keep,  have,  sell  or  offer  for  sale  in  said  town  any  such  cream. 
The  term  "cream  "  means  the  fatty  portions  of  pure  milk  which  rise  to 
the  surface  when  milk  is  left  at  rest,  or  which  are  separated  by  other 
means.  The  term  "cream  which  is  adulterated,"  as  used  in  this  sec- 
tion, means  any  cream  to  which  any  foreign  substance  has  been  added. 

Sec.  12.  The  Health  Officer  and  his  assistants  and  deputies  shall  have 
authority  to  stop  and  inspect,  or  cause  to  be  inspected,  any  wagon,  cart, 
train  or  other  vehicle  used  in  delivering  milk,  or  any  store,  depot,  shop, 
creamery  or  any  place  where  milk  is  offered  for  sale  or  sold,  and  to  take 
samples  of  milk  from  wagons,  carts,  trains  or  any  other  place  where 
milk  is  sold  or  offered  for  sale,  for  the  purpose  of  enforcing  the  provis- 
ions of  this  ordinance. 

Sec.  13.  Milk  must  not  be  kept  for  sale  or  stored  in  any  stable,  or 
milk-house  that  is  connected  with  a  stable,  or  in  any  room  used  for 
sleeping  or  domestic  purposes  or  opening  into  same,  nor  in  unclean  or 
rusty  cans. 

Milk  must  not  be  transferred  from  cans  to  bottles  or  other  vessels  on 
streets  or  at  railroad  depots.  Milk  must  not  be  sold  in  bottles,  except 
under  the  following  rules  : 

Bottles  must  be  washed  clean  with  hot  wrater  solution  of  soap  or  soda, 
or  some  other  alkali,  and  then  with  hot  water  before  filling. 

Bottles  must  not  be  filled  except  at  the  dairy  or  creamery,  and  in  the 
town  only  in  rooms  .so  situated  as  to  prevent  contamination  of  the  milk 
by  dust  or  other  impurities  from  the  streets  or  elsewhere. 

Bottles  must  not  be  washed  or  filled  with  milk  in  any  rooms  used  for 
sleeping  or  domestic  purposes,  or  opening  into  the  same. 

The  vessels  in  which  milk  is  kept  for  sale  must  be  protected  by  means 
of  a  suitable  covered  receptacle  and  so  placed  in  the  store  as  to  prevent 
dust  from  the  street  or  other  impurities  falling  into  it. 

All  cattle  condemned  as  tuberculous  shall  be  removed  from  the  prem- 
ises within  one  week  thereafter. 


APPENDIX  A.  199 

When  any  person  having  a  permit  hereumler  shall  sell  or  deliver  to 
any  customer  any  tickets  or  tags  representing  any  milk  or  cream  to 
which  the  customer  is  entitled,  the  same  shall  be  in  the  form  of  coupon 
tickets,  or  be  metal  tags,  so  as  to  insure  cleanliness. 

Sec.  14.  Nothing  herein  contained  shall  be  construed  to  prevent  or 
prohibit  the  use,  sale  or  manufacture  of  what  is  known  as  condensed 
milk,  or  what  is  known  as  buttermilk,  provided  the  same  are  made,  com- 
pounded and  prepared  from  milk  not  lower  than  the  standard  provided 
in  this  ordinance,  and  provided  further  that  said  condensed  milk  or 
buttermilk  are  in  sound,  wholesome  condition,  and  provided  also  that  in 
the  case  of  condensed  and  dried  milks,  the  properties  of  milk  solids 
shall  be  equivalent  to  twelve  (12)  per  centum  of  milk  solids  in  crude 
milk,  and  that  of  such  solids  twenty-five  (25)  per  centum  shall  be  fat. 

Sec.  15.  Any  person  who  shall  violate  any  of  the  provisions  or 
requirements  of  this  ordinance  shall  be  deemed  guilty  of  a  misdemeanor 
and  upon  conviction  thereof,  shall  be  punished  by  a  fine  of  not  less  than 
ten  (10)  dollars,  nor  more  than  two  hundred  and  fifty  (250)  dollars,  or  by 
imprisonment  in  the  county  jail  of  Alameda  county  for  not  more  than 
ninety  (90)  days;  or  by  both  such  fine  and  imprisonment. 

The  judgment  imposing  the  fine  may  provide  for  its  collection  by  im- 
prisonment in  the  county  jail  of  Alameda  county  for  the  time  and  in  the 
manner  provided  by  law. 

Sec.  16.  All  ordinances  and  parts  of  ordinances  in  conflict  with  the 
provisions  of  this  ordinance  are  hereby  repealed. 

Sec.  17.  This  ordinance  shall  take  effect  and  be  in  force  and  effect 
from  and  after  its  final  passage. 

Sec.  18.  This  ordinance  is  hereby  ordered  to  be  printed  and  pub- 
lished (with  the  ayes  and  noes)  for  two  days  in  the  Berkeley  Daily 
Gazette.  which  newspaper  is  hereby  designated  for  that  purpose. 


APPENDIX  B. 


CHICAGO  TUBERCULIN  TEST  ORDINANCE  AND  RULES  OF  THE 
DEPARTMENT  OF  HEALTH. 


ORDINANCES  REQUIRING  TUBERCULIN  TEST  OF  ALL  Cows  SUPPLYING 
MILK  AND  MILK  PRODUCTS. 


Be  it  ordained  by  the  City  Council  of  the  City  of  Chicago : 

MILK. 

SECTION  1.  No  milk,  cream,  buttermilk  or  ice  cream  shall  be  sold, 
offered  for  sale,  exposed  for  sale  or  kept  with  the  intention  of  selling 
within  the  City  of  Chicago  after  January  1,  A.  D.  1909,  unless  such  milk 
or  cream  or  the  milk  or  cream  contained  in  buttermilk  and  ice  cream, 
be  obtained  from  cows  that  have  given  a  satisfactory  negative  tuberculin 
test  within  one  year ;  the  cows  having  been  satisfactorily  tested  shall  be 
marked  "tuberculin  tested"  and  shall  be  numbered  and  a  certificate 
shall  be  filed  with  the  division  of  milk  inspection  of  the  Department  of 
Health  of  the  City  of  Chicago  upon  forms  furnished  by  the  Commissioner 
of  Health,  giving  the  number,  a  brief  description  of  the  animal,  the  date 
of  the  taking  of  said  test  and  the  name  of  the  owner.  Said  certificate 
shall  be  signed  by  the  person  making  such  test ;  provided,  however,  that 
from  January  1,  1909,  for  a  period  of  five  years,  to  wit,  until  January  1, 
1914,  milk  or  cream  or  buttermilk  and  ice  cream  made  from  milk  or 
cream,  obtained  from  cows  not  tuberculin  tested  or  not  free  from  tubercu- 
losis, may  be  sold  within  the  City  of  Chicago  if  the  milk  or  cream  from 
said  cows  is  pasteurized  according  to  the  rules  and  regulations  of  the 
Department  of  Health  of  the  City  of  Chicago. 

SECTION  2.  Any  milk,  cream,  buttermilk  or  ice  cream  offered  for  .sale, 
exposed  for  sale  or  kept  with  the  intention  of  selling  within  the  City  of 
Chicago  wThich  shall  be  found  within  the  City  in  violation  of  Section  1, 
shall  be  forthwith  seized,  condemned  and  destroyed  by  the  milk  and 
food  inspectors  or  other  duly  authorized  agents  or  employes  of  the  De- 
partment of  Health  of  the  City  of  Chicago. 

SECTION  3.  This  ordinance  shall  be  in  full  force  and  effect  from  and 
after  January  1,  1909. 

BUTTP:R. 
Be  it  ordained  by  the  City  Council  of  the  City  of  Chicago : 

SECTION  1.  No  butter  shall  be  sold  or  offered  for  sale  or  kept  with 
the  intention  of  selling  in  the  City  of  Chicago  after  January  1 ,  1909,  un- 


APPENDIX  B.  201 

less  such  butter  be  made  from  milk  or  cream  obtained  from  cows  that 
have  given  a  satisfactory  negative  tuberculin  test  within  one  year ;  pro- 
vided, however,  that  from  January  1,  1909,  for  a  period  of  five  years,  to 
wit,  until  January  1,  1914,  butter  made  of  milk  obtained  from  cows  not 
tuberculin  tested  or  not  free  from  tuberculosis  may  be  sold  in  the  City 
of  Chicago  if  the  milk  or  cream  from  which  such  butter  was  made  was 
pasteurized  according  to  the  rules  and  regulations  of  the  Department  of 
Health  of  the  City  of  Chicago. 

SUCTION  2.  It  shall  be  unlawful  to  sell  any  butter  in  the  City  of 
Chicago,  unless  there  be  stamped  on  the  package  in  plainly  legible  let- 
ters of  not  less  than  one-eighth-inch  type  :  ' '  Made  of  milk  (or  cream) 
from  cows  free  from  tuberculosis  as  shown  by  tuberculin  test, ' '  or,  "Made 
from  milk  (or  cream)  pasteurized  according  to  the  rules  and  regulations 
of  the  Department  of  Health  of  the  City  of  Chicago." 

SKCTION  3.  Any  butter  offered  for  sale,  exposed  for  sale  or  kept  with 
the  intention  of  selling  in  the  City  of  Chicago,  which  shall  be  found 
within  the  city  in  violation  of  this  ordinance,  shall  be  forthwith  sei/ed, 
condemned  and  destroyed  by  the  milk  and  food  inspectors  or  other  duly 
authorized  agents  or  employes  of  the  Department  of  Health  of  the  City 
of  Chicago. 

SKCTION  4.  This  ordinance  shall  be  in  full  force  and  effect  from  and 
after  January  1,  1909. 

CHEESE. 

Be  it  ordained  by  the  City  Council  of  the  City  of  Chicago : 

SKCTION  1.  No  domestic  cheese  shall  be  sold  or  offered  for  sale  or 
kept  with  the  intention  of  selling  in  the  City  of  Chicago  after  January  1, 
1909,  unless  .such  cheese  be  made  from  milk  or  cream  obtained  from 
cows  that  have  given  a  satisfactory  negative  tuberculin  test  within  one 
year  ;  provided,  however,  that  from  January  1,  1909,  for  a  period  of  five 
years,  to  wit,  until  January  1,  1914,  domestic  cheese  made  of  milk  obtained 
from  cows  not  tuberculin  tested  or  not  free  from  tuberculosis,  may  be 
sold  in  the  City  of  Chicago  if  the  milk  or  cream  from  which  such  cheese 
was  made  was  pasteurized  according  to  the  rules  and  regulations- of  the 
Department  of  Health  of  the  City  of  Chicago. 

SKCTION  2.  It  shall  be  unlawful  to  sell  any  such  cheese  in  the  City 
of  Chicago  unless  there  be  stamped  on  the  package  in  plainly  legible 
letters  of  not  less  than  one-eighth-inch  type  :  "  Made  of  milk  (or  cream) 
from  cows  free  from  tuberculosis  as  shown  by  tuberculin  test, "  or  ' '  Made 
from  milk  (or  cream)  pasteurized  according  to  the  rules  and  regulations 
of  the  Department  of  Health  of  the  City  of  Chicago." 

SECTION  3.  Any  cheese  offered  for  sale,  exposed  for  sale  or  kept  with 
the  intention  of  selling  in  the  City  of  Chicago,  which  shall  be  found 
within  the  citv  in  violation  of  this  ordinance,  shall  be  forthwith  seized, 


202  APPENDICES. 

condemned  and  destroyed  by  the  milk  and  food  inspectors  or  other  duly 
authorized  agents  or  employes  of  the  Department  of  Health  of  the  City 
of  Chicago. 

SECTION  4.     This  ordinance  shall  be  in  full  force  and  effect  from  and 
after  January  1,  1909. 


RULES  RKGUI.ATING  THE  TUBERCULIN  TESTING  OF  Cows. 

Rule  1.  Who  May  Make  the  Test.]  Tuberculin  tests  made  on  ani- 
mals supplying  the  City  of  Chicago  with  milk  or  milk  products  may  be 
made  by  licensed  graduate  veterinarians,  federal  or  state  veterinarians, 
federal,  state  or  city  dairy  and  milk  inspectors  and  by  persons  regularly 
employed  by  the  Chicago  Department  of  Health  for  that  purpose. 

Rule  2.  The  Test  to  be  Employed.]  The  regular  injection  method 
of  tuberculin  testing  shall  be  employed.  The  temperature  shall  be 
taken  at  least  four  times  on  the  da}-  preceding  the  inoculation,  and  at 
least  six  times  on  the  day  following  the  inoculation,  at  not  less  than  two 
hour  intervals.  A  rise  of  two  degrees  over  the  average  temperature  on 
the  day  preceding  the  inoculation  shall  be  considered  a  positive  test. 
If  a  rise  of  from  one  and  a  half  to  two  degrees  is  obtained,  the  results 
shall  be  considered  doubtful,  and  the  animal  subjected  to  a  later  retest. 
Animals  that  have  been  added  to  the  herds  within  the  last  six  weeks 
shall  be  tested  by  the  ordinary  injection  test  supplemented  by  Cal- 
mette's  Ophthalmic  Test,  and  a  positive  result  with  either  one  or  the 
other  shall  condemn  the  animal.  The  Department  of  Health  shall  have 
the  power  to  require  the  retesting  of  all  animals  submitted  for  milk  sup- 
ply by  the  Calmette  Ophthalmic  method  or  any  other  method  to  be 
decided  on  in  the  future. 

Rule  3.  The  Numbering  and  Tagging  of  Animals.]  All  tested  ani- 
mals shall  bear  an  indestructible  tag  indicating  the  series,  and  also  the 
number  assigned  to  the  animal.  Tags  placed  by  federal,  state  and 
municipal  inspectors  will  designate  by  abbreviations  or  otherwise  the 
series  represented.  Veterinarians  supplying  the  numbered  tags  must 
have  their  initials  or  some  other  distinctive  mark  appear  on  the  tag  with 
the  number  to  indicate  the  series. 

Rule  4.  Statement  to  be  Submitted.]  A  statement  must  be  filed  with 
the  Division  of  Milk  Inspection  for  every  tuberculin  tested  animal  sup- 
plying the  City  of  Chicago  with  milk  or  milk  products.  This  statement 
must  indicate  the  number  and  series  given  to  the  animal,  which  number 
and  series  must  correspond  with  the  tag  or  mark  worn  by  the  animal. 
This  statement  must  also  state  the  age  and  color  of  the  animal,  and  any 
other  distinctive  marks  shown  by  the  animal.  In  addition  the  statement 
must  show  the  temperature,  record  of  the  animal  on  the  days  preceding 
and  following  the  test,  the  date  and  the  exact  time  of  taking  these 


APPENDIX    B.  203 

.temperatures  and  the  date  and  time  of  making  the  injection  and  amount 
and  kind  of  tuberculin  used  ;  the  name  of  the  owner  and  the  signature  of 
the  person  making-  the  test,  together  with  the  official  capacity  of  said 
person  or  persons  making  the  test,  and  their  address.  The  statement 
submitted  shall  also  indicate  the  date  of  the  last  tuberculin  test  made 
upon  the  animal  and  the  method  of  making  this  test,  and  the  length  of 
time  that  the  animal  has  been  in  the  herd. 


Rrucs  REGULATING  THE  PASTEURIZING  OF  MILK  AND  MILK  PRODUCTS. 


The  following  rules  shall  regulate  the  pasteurizing  of  milk  and  milk 
products  offered  for  sale,  exposed  for  sale  or  kept  with  the  intention  of 
selling  within  the  City  of  Chicago,  after  January  1st,  A.  D.  1908: 

Rule  1.  Milk" and  Skimmed  Milk.]  Milk  and  skimmed  milk  shall 
not  contain  more  than  100,000  bacteria  per  cubic  centimeter  from  May 
1st  to  September  30th,  and  not  over  50,000  bacteria  per  cubic  centimeter 
between  October  1st  and  April  30th. 

Rule  2.  Cream  and  Ice  Cream.]  Cream  and  icecream  shall  not  con- 
tain more  than  200,000  bacteria  per  cubic  centimeter  from  May  1st  to 
September  30th,  and  not  over  100,000  bacteria  per  cubic  centimeter 
between  October  1st  and  April  30th. 

Rule  3.  Milk,  Skimmed  Milk,  Buttermilk,  Cream  and  Ice  'Cream.] 
An  original  package  of  pasteurized  milk,  skimmed  milk,  buttermilk, 
cream  or  ice  cream,  exposed  to  the  temperature  of  the  room  for  48  hours 
and  stoppered  with  a  sterile  cotton  plug,  shall  not  show  evidences  of 
putrefaction,  after  being  so  exposed. 

Rule  4.  Skimmed  Milk  and  Ice  Cream.]  Skimmed  milk  and  ice 
cream  shall  give  a  negative  test  when  treated  in  the  following  manner  : 

To  5  cc.  of  the  pasteurized  product  add  two  drops  of  a  2  per  cent  solu- 
tion of  paraphenylenediamin,  and  one  drop  of  a  2  per  cent  solution  of 
hydrogen  peroxide,  and  agitate. 

Not  more  than  a  tinge  of  blue  shall  be  obtained  by  this  test  within  30 
seconds  after  mixing. 

Rule  5.     Butter.]     Butter  shall  respond  to  the  following  test: 

25  grams  of  pasteurized  butter  placed  in  a  small  beaker  and  heated  by 
being  placed  in  water  at  60  degrees  centigrade,  the  clear  butter  fat  then 
poured  off  and  the  remaining  liquid  then  diluted  with  an  equal  volume 
of  water.  The  mixture  thus  obtained  is  now  treated  with  two  drops  of 
a  2  per  cent  solution  of  paraphenylenediamin  and  one  drop  of  a  solution 
of  2  per  cent  hydrogen  peroxide. 

When  thus  treated  not  more  than  a  perceptible  blue  color  shall  be 
obtained  within  30  seconds  after  mixing. 

Rule  6.  Pasteurizing  Temperatures.]  All  pasteurized  milk,  cream, 
skimmed  milk,  milk  products,  and  milk  and  cream  used  in  the  produc- 


204  APPENDICES. 

tion  of  milk  products  shall  be  pasteurized  in  accordance  with  the  follow- 
ing regulations  : 

(A)  Continuous  Pasteurization.]     In  all  continuous  pasteurization  the 
milk  and  cream  shall  be  heated  to  a  temperature  which  shall  be  deter- 
mined and  fixed  by  the  Department  of  Health  for  each  machine  at  a 
point  corresponding  to  the  temperature  required  to  kill  99  per  cent  of 
the  bacteria  and  all   pathogenic  bacteria  contained  in  the  raw  product. 
For  this  determination  ordinary  raw  milk  containing  in  the  neighbor- 
hood of  3,000,000  bacteria  shall  be  used  and  the  pasteurized  product  shall 
be  collected  as  it  flows  from  the  cooling  apparatus. 

All  continuous  pasteurizers  shall  be  equipped  with  a  feeding  pipe 
which  is  so  constructed  that  the  pasteurizer  cannot  be  fed  in  excess  of 
its  normal  w-orking  capacity  ;  that  is,  in  excess  of  the  working  capacity 
of  the  machine  at  which  99  per  cent  of  the  bacteria  are  killed  when  the 
required  amount  of  heat  is  applied. 

All  continuous  pasteurizers  operated  outside  of  the  city  limits,  for  the 
production  of  pasteurized  milk  and  milk  products  to  be  sold  in  the  City 
of  Chicago  shall  be  equipped  with  an  apparatus  regulating  automatically 
the  supply  of  steam  and  heat,  so  as  to  correspond  with  and  produce  the 
required  temperature  of  the  outflow  of  the  pasteurized  product.  These 
automatic  thermo  regulators  shall  be  accurate  and  must  be  approved  by 
the  Commissioner  of  Health  before  being  installed. 

A  recording  apparatus  shall  be  installed  upon  all  continuous  pasteur- 
izers operated  within  the  city  limits  so  as  to  record  during  operation  the 
temperature  of  the  pasteurized  product  as  it  flows  from  the  heater.  The 
thermometer  of  this  recording  apparatus  must  be  accurate  and  kept 
emerged  in  the  milk  in  such  a  way  that  it  is  not  exposed  to  escaping 
steam  or  other  heat,  except  the  heated  milk. 

The  records  made  by  this  recording  thermometer  must  be  accurate  and 
made  in  a  chamber  which  is  kept  under  lock  and  key  in  the  control  of 
the  Department  of  Health. 

The  automatic  thermo  regulating  and  recording  apparatus  may  be  com- 
bined into  one  instrument  and  it  is  recommended  that  all  pasteurizers  be 
equipped  with  both  appliances  or  the  combination  apparatus. 

(B)  Held  Pasteurization.]      Whenever  milk  is  held  during  pasteuri- 
zation in  such  a  manner  that  the  process  of  pasteurizing  is  not  a  contin- 
uous one,  namely,  a  continuous  flow  of  milk  through  the  heating  or  heat 
retaining  chamber,  the  process  shall  be  designated  as  ' '  Held  Pasteuriz- 
ation."   Such  methods  of  pasteurization  and  pasteurization  appliances  or 
systems  installed  and  used  shall  be  examined  and  approved  by  the  Com- 
missioner of  Health,  or  his  duly  appointed  representatives,  when  all  of 
the  following  requirements  are  fulfilled  : 

1.  When  the  pasteurized  product  shows  that  over  99  per  cent  of  the 
bacteria  and  all  pathogenic  bacteria  contained  in  the  raw  product  have 
been  destroved. 


APPENDIX    B.  205 

2.  When  the  mechanism  of  the  pasteurizer  or  pasteurizing  system  is 
such  that  the  three  important  elements,  namely  :  the  temperature,  time 
of  exposure,  and  the  quantity  of  milk  exposed  at  one  time  can  be  readily 
kept  under  control  and  observation  by  the  Department  of  Health. 

3.  When  the  following  conditions  are  complied  with  : 

A  uniform  heating  of  140  degrees  F.  maintained  for  20  minutes  ;  150 
degrees  F.  maintained  for  15  minutes  ;  155  degrees  F.  maintained  for  5 
minutes;  160  degrees  F.  maintained  for  ll/2  minutes;  165  degrees  F. 
maintained  for  1  minute. 

The  time  shall  be  calculated  from  the  period  that  the  entire  quantity 
reaches  the  required  temperature. 

Rule  7.  Cooling  Temperatures.]  The  pasteurized  product  shall  be 
cooled  at  once  to  a  temperature  of  45  degrees  F.  or  less.  This  cooling 
shall  be  so  conducted  that  the  pasteurized  product  is  not  exposed  to  the 
air  or  other  contamination.  This  cooling  apparatus  shall  be  so  con- 
structed that  it  can  be  readily  cleaned  and  sterilized. 


APPENDIX  C. 


DULUTH  MILK  ORDIXAXCK. 

Ax  ORDINAXCK.TO  PROVIDE  FOR  THE  INSPECTION  OF  MII.K,  DAIRIES 

AND  DAIRY  HERDS  AND  TO -LICENSE  AND  REGI'LATE  THE  SALE 

AND  DISPOSITION  OF  MII.K  IN  THE  CITY  OF  DCI.UTH. 

The  Common  Council  of  the  City  of  Duluth  do  ordain  as  follows  : 

Section  1.  That  from  and  after  the  passage  and  approval  of  this  ordi- 
nance no  person  shall  engage  in  the  sale  or  disposition  of  milk  within 
the  City  of  Duluth  without  first  having  obtained  a  license  so  to  do  in  the 
manner  hereinafter  provided. 

Section  2.  Any  person  desiring  a  license  to  engage  in  the  sale  or  dis- 
position of  milk,  as  provided  in  section  1  hereof,  shall  first  make  appli- 
cation therefor  to  the  Common  Council  by  filing  with  the  commissioner 
of  health  of  the  City  of  Duluth  for  presentation  by  him  to  the  Common 
Council  of  said  city,  an  application  in  writing  therefor,  which  said  appli- 
cation shall  set  forth  with  reasonable  exactness  the  name  and  place  of 
residence  of  the  applicant,  the  exact  location  or  place  from  which  the 
applicant  obtains  or  is  to  obtain  his  milk,  and  if  the  applicant  is  not  a 
producer  of  milk,  then  the  number  of  cows  in  his  dairy  herd,  the  name 
of  the  person  or  persons  .from  whom  he  obtains  or  is  to  obtain  his  milk 
for  sale  or  distribution,  and  if  said  applicant  is  a  producer  of  milk,  or  if 
he  is  not  a  producer  of  milk,  the  number  of  COWTS  in  the  dairy  herd  of 
the  person  or  persons  from  wThom  he  obtains  or  is  to  obtain  his  milk  ; 
and  said  application  shall  further  set  forth  the  manner  in  which  the 
applicant  intends  to  dispose  of  his  milk  wThen  licensed,  according  to  the 
provisions  of  this  ordinance,  and  shall  be  signed  by  the  applicant,  and 
when  received  by  the  commis'sioner  of  health  shall  be  placed  on  file  and 
the  name  of  the  applicant  shall  be  registered  in  a  book  of  registration 
kept  for  such  purpose. 

Section  3.  The  filing  of  the  application  provided  for  in  the  next  pre- 
ceding section  shall  authorize  the  applicant  to  engage  in  the  sale  or  dis- 
posal of  milk  and  to  continue  in  the  prosecution  of  that  business,  if  he 
shall,  at  the  time  of  the  filing  of  the  application,  be  engaged  in  the  busi- 
ness of  selling  or  distributing  milk,  until  the  Common  Council  takes 
action  thereon  and  either  issues  a  license  to  the  applicant  or  refuses  so 
to  do. 

Section  4.  Any  such  applicant,  or  any  person  from  whom  such  appli- 
cant obtains  or  is  to  obtain  his  milk,  shall  permit  the  officers  of  the 


AIM'KNDIX  C.  207 

department  of  health  of  the  City  of  Duluth  to  inspect  the  dairy  and  dairy 
herds  of  such  applicant,  or  the  dain-  and  dain-  herd  of  the  person  or 
persons  from  whom  the  applicant  obtains  or  is  to  obtain  his  milk,  to- 
gether with  all  appliances  and  milk  vessels  used  therein,  and  any  refusal 
upon  the  part  of  such  applicant  or  upon  the  part  of  the  person  or  per- 
sons from  whom  such  applicant  obtains  or  is  to  obtain  his  milk  to  permit 
the  inspection  above  referred  to  shall  be  deemed  a  sufficient  ground 
upon  which  the  Common  Council  may  refuse  to  issue  the  license  applied 
for. 

Section  5.  Upon  the  filing  of  the  application  with  the  commissioner 
of  health,  as  provided  in  section  2  thereof,  said  commissioner,  or  an 
authori/.ed  inspector  or  veterinary,  acting"  under  his  instructions,  shall 
proceed,  without  unnecessary  delay,  to  inspect  the  dairy  and  dairy  herd 
of  such  applicant,  or  the  dairy  and  dairy  herd  of  the  person  or  persons 
from  whom  the  applicant  obtains  or  is  to  obtain  his  milk  for  sale  or  dis- 
tribution within  the  corporate  limits  of  the  City  of  Duluth,  and  it  shall 
be  the  duty  of  said  commissioner  of  health  to  make  or  cause  to  be  made, 
under  his  direction  and  supervision,  an  examination  and  inspection,  not 
only  of  each  and  even-  animal  producing  milk  for  sale  or  consumption 
within  the  corporate  limits  of  said  City  of  Duluth,  belonging  to  or  con- 
trolled by  the  said  applicant  or  the  person  from  whom  said  applicant 
obtains  or  is  to  obtain  his  milk,  but  also  of  each  and  every  COWT,  heifer, 
bull,  steer  or  calf  over  the  age  of  six  months  in  the  dairy  or  dairy  herd 
of  such  person,  for  the  purpose  of  detecting  the  presence  or  absence  of 
tuberculosis  or  any  other  contagious  or  infectious  disease,  and  said  com- 
missioner of  health,  or  his  said  authorized  inspector,  acting  under  his 
direction  and  supervision  in  making  such  inspection  and  examination,  is 
hereby  authorized  to  use  what  is  commonly  known  as  the  tuberculin  test 
as  a  diagnostic  agent  for  the  detection  of  tuberculosis. 

Section  6.  After  such  examination  and  inspection  of  the  dairies  and 
dairy  herds  as  in  the  next  preceding  section  provided,  an  authorized 
agent  of  the  department  of  health  of  the  City  of  Duluth  shall  tag  each 
and  every  animal  so  examined,  which  tag  shall  be  of  such  character  as 
to  afford  a  permanent  record  of  such  examination,  nor  shall  such  tag  be 
altered,  mutilated  or  removed  by  any  one  other  thai!  an  authorized  agent 
of  the  health  department  of  the  City  of  Duluth,  and  the  result  of  the 
same  as  regards  the  presence  or  absence  from  an  infectious  or  contagious 
disease,  and  immediately  thereafter  and  without  undue  or  unnecessary 
delay  the  commissioner  of  health  shall  present  the  application  in  section 
2  hereof  provided  for  to  the  Common  Council  of  the  City  of  Duluth,  and 
shall  accompany  it  with  a  report  which  shall  contain  the  result  of  the 
examination  and  inspection  of  the  dairy  and  dairy  herd  of  the  applicant, 
or  of  the  dairy  and  dairy  herd  of  the  person  or  persons  from  whom  the 
applicant  obtains  or  is  to  obtain  his  milk  for  sale  or  distribution  within 
the  corporate  limits  of  the  City  of  Duluth  ;  and  the  commissioner  of 


208  APPENDICES. 

health  shall  also  state  in  such  report  what  disposition,  if  any,  has  been 
made  by  the  applicant  or  the  person  or  persons  from  whom  the  applicant 
obtains  or  is  to  obtain  his  milk  of  the  animals  which  were  found  to  be 
affected  with  tuberculosis  or  any  other  contagious  or  infectious  disease, 
if  any  there  were,  and  wrhether  or  not  an}-  animals  so  diseased  are  used 
by  the  applicant  or  the  person  or  persons  from  whom  the  applicant  ob- 
tains or  is  to  obtain  his  milk  for  the  production  of  milk  for  sale  or  dis- 
tribution for  consumption  within  the  corporate  limits  of  the  City  of 
Duluth. 

Section  7.  The  Common  Council  shall  thereupon,  after  proper  investi- 
gation, whether  from  a  consideration  of  .such  report  or  from  other  sources, 
adjudge  and  determine  what  applicants  may  be  entitled  to  obtain  a 
license  for  the  sale  or  distribution  of  milk  within  the  corporate  limits  of 
the  City  of  Duluth,  and  shall  thereupon  by  resolution  grant  the  license 
applied  for  to  such  of  the  applicants  as  ma}-  be,  in  the  opinion  of  the 
Common  Council,  entitled  thereto  under  the  provisions  of  this  ordinance. 

Section  8.  It  shall  thereupon  be  the  duty  of  the  commissioner  of 
health,  upon  due  notice  from  the  city  clerk  of  the  passage  of  the  resolu- 
tion or  resolutions  in  the  next  preceding  section  provided  for,  to  issue  a 
license  or  licenses  to  sell  or  distribute  milk  within  the  corporate  limits 
of  the  City  of  Duluth  to  each  applicant  named  in  such  resolution  or  reso- 
lutions as  is  entitled  thereto,  which  said  license  shall  be  numbered  and 
signed  by  the  commissioner  of  health,  and  a  record  thereof  shall  be  kept 
in  the  book  of  registration  provided  for  in  section  2  hereof,  and  said 
license  shall  be  valid  and  effective  for  the  period  of  one  year  from  and 
after  the  date  of  its  issuance,  and  no  longer. 

Section  9.  Each  licensee  shall  cause  his  name  and  his  place  of  busi- 
ness and  the  number  of  his  license  to  be  legibly  placed  in  a  conspicuous 
place  on  the  outer  side  of  all  carriages,  wagons,  sleighs  or  other  vehicles 
used  by  him  in  the  sale  or  distribution  of  milk  within  the  corporate 
limits  of  the  City  of  Duluth,  and  all  licensees  who  sell  milk  from  stores 
or  shops  shall  keep  their  licenses  constantly  posted  in  a  conspicuous 
place  upon  the  wall  of  the  room  within  which  such  sale  of  milk  is  prose- 
cuted or  carried  on. 

Section  10.  No  person  shall  offer  or  expose  for  sale,  or  sell  or  dis- 
tribute or  deliver  for  sale  or  consumption  any  unclean,  impure,  unhealthy, 
unwholesome  or  adulterated  milk,  and  no  person  shall  keep  animals  for 
the  production  of  milk  for  sale  or  distribution  within  the  corporate  limits 
of  the  City  of  Duluth  in  an  over-crowded  condition,  or  in  barns  or  stables 
or  other  buildings  which  are  not  properly  ventilated,  or  which  are  in  an 
unfit  and  unclean  condition  from  any  cause,  nor  shall  any  person  draw 
or  suffer  to  be  drawn  milk  from  animals  which  are  themselves  in  an 
unfit  or  unclean  condition,  or  from  animals  which  are  affected  with 
tuberculosis,  or  any  other  form  of  disease,  or  from  animals  which  are  fed 
either  wholly  or  in  part  upon  fermented  distillery  waste  or  decomposed 


APPKNDIX   C.  209 

brewery  grains  or  the  waste-  of  vinegar  factories,  in  a  fermented  condi- 
tion, or  upon  any  other  form  of  food  which  is  calculated  to  produce  milk 
which  is  unhealthy  or  unwholesome,  or  from  animals  which  are  supplied 
with  water  which  is  impure  and  unwholesome,  nor  shall  any  person 
keep  or  suffer  to  he  kept  any  milk  or  milk  product  intended  for  sale  or 
distribution  in  unfit  or  unclean  vessels,  nor  in  any  unfit  or  unclean  room 
or  building,  or  in  any  room  or  building  used  as  a  sleeping  apartment 
or  for  am  other  purpose  incompatible  with  the  proper  preservation  of 
.the  cleanliness,  wholesomeness  or  healthy  condition  of  the  milk  or  milk 
vessels  kept  therein,  and  all  milk  thus  kept  or  produced  is  hereby  de- 
clared to  be  unclean,  impure,  unhealthy  and  unwholesome  milk,  within 
the  meaning  of  this  section,  and  any  milk  which  is  shown  by  analysis  to 
contain  a  preservative  or  any  other  substance  or  substances  of  any  char- 
acter whatever  not  natural  or  normal  constituents  of  milk,  or  to  have 
been  deprived  either  wholly  or  in  part  of  any  constituent  naturally  or 
normally  contained  in  milk,  or  which  is  shown  to  contain  more  than 
eighty-seven  (87)  per  cent  of  water  fluids,  or  less  than  thirteen  (13)  per 
cent  of  milk  solids,  of  which  less  than  three  and  a  half  (^/4)  per  cent 
shall  be  fat,  is  hereby  declared  to  be  adulterated  milk  within  the  mean- 
ing of  this  section,  and  any  such  unclean,  impure,  unhealthy,  unwhole- 
some or  adulterated  milk  may  be  sei/.ed  and  confiscated  by  the  commis- 
sioner of  health  or  his  duly  appointed,  qualified  and  authorized  inspectors. 

Section  11.  No  person  shall,  within  the  corporate  limits  of  the  City  of 
Duluth,  have  in  his  possession  wTith  intent  to  sell,  offer  or  expose  for 
sale,  or  sell  or  deliver  for  sale  or  consumption,  in  any  store  or  place  of 
business,  or  from  any  wagon,  sleigh,  cart  or  other  vehicle  used  in  the 
distribution  or  sale  of  milk,  any  milk  from  which  the  cream  has  been 
removed,  or  milk  commonly  known  as  "skimmed  milk,"  without  first 
marking  the  can  or  package  containing  said  milk  and  from  which  said 
milk  is  delivered  to  the  purchaser  or  customer  with  the  words  "skimmed 
milk"  in  large,  plain  letters,  each  letter  being  at  least  one  inch  high 
and  a  half  inch  wide,  and  to  be  placed  in  such  position  as  to  be  easily 
seen  when  such  milk  is  sold  and  delivered. 

Section  12.  In  order  to  carry  out  the  provisions  and  purposes  of  this 
ordinance,  the  commissioner  of  health,  and  all  other  officials,  inspectors 
and  employes  of  the  department  of  health  in  the  City  of  Duluth,  shall 
have  the  right  at  any  and  all  times  to  enter  upon  or  in  the  premises  of 
any  person  licensed  under  the  provision  of  this  ordinance,  to  examine 
and  inspect  the  dairy  and  dairy  herd  of  such  licensee,  and  to  appropriate 
a  reasonable  amount  of  any  milk  or  milk  product  in  the  possession  or 
under  the  control  of  such  licensee  for  the  purpose  of  use  as  samples  and 
for  inspection  or  test,  and  they  shall  also  have  the  right  to  enter  upon 
or  into  the  premises  of  any  person  or  persons  from  whom  such  licensee 
obtains  his  milk  for  sale,  to  inspect  and  examine  the  dairy  and  dairy 
herd  of  such  person  or  persons  ;  and  each  licensee,  under  the  terms 


210  APPENDICES. 

hereof,  shall  give  at  least  three  days  notice  in  writing  to  the  commissioner 
of  health  of  an  intention  on  his  part  to  obtain  his  milk  from  other  per- 
sons than  those  named  in  his  original  application,  and  any  failure  upon 
his  part  so  to  do,  or  any  refusal  upon  the  part  of  said  licensee  or  upon 
the  part  of  the  person  or  persons  from  whom  said  licensee  obtains  his 
milk,  to  allow  such  entry  or  inspection  as  may  be  required  under  the 
terms  of  this  ordinance  shall  be  followed  by  an  immediate  revocation  of 
the  license  of  such  person  or  persons  by  the  commissioner  of  health. 

Section  13.  It  shall  be  the  duty  of  the  commissioner  of  health  to  cause 
the  dairy  and  dairy  herd  of  all  licensees  hereunder,  and  the  dairies  and 
dairy  herds  of  the  person  or  persons  from  whom  such  licensees  obtain 
their  milk,  to  be  inspected  from  time  to  time,  and  if  the  conditions 
which  are  required  as  a  prerequisite  to  obtaining  a  license  under  the 
provisions  of  this  ordinance  are  not  constantly  maintained,  then  it  shall 
be  the  duty  of  the  commissioner  of  health  to  report  the  same  to  the 
Common  Council  and  make  such  recommendations  in  regard  thereto  as 
he  may  deem  proper. 

Section  14.  The  commissioner  of  health  may  appoint,  at  such  com- 
pensation as  may  be  fixed  upon  and  determined  by  the  Common  Council, 
such  additional  inspectors  or  employes  as  may  be  necessary  for  the  pur- 
pose of  carrying  out  the  provisions  of  this  ordinance,  and  the  salaries  of 
such  additional  inspectors  and  other  expenses  incidental  to  the  enforce- 
ment of  this  ordinance  shall  be  payable  out  of  the  general  fund,  and  it 
is  hereby  made  the  duty  of  the  commissioner  of  health  to  enforce  the 
provisions  hereof. 

Section  15.  Any  person  violating  any  of  the  provisions  of  this  ordi- 
dance  shall,  upon  conviction  thereof,  be  punished  by  a  fine  of  not  less 
than  Ten  (10)  Dollars  nor  more  than  Thirty  (30)  Dollars,  or  by  imprison- 
ment for  not  less  than  ten  (10)  nor  more  than  ninety  (90)  days,  and 
by  the  revocation  of  any  license  which  may  have  been  granted  to  such 
persons  under  the  terms  of  this  ordinance,  such  revocation  to  be  immedi- 
ately made  by  the  commissioner  of  health  of  the  City  of  Duluth. 

Section  16.  All  ordinances  or  parts  of  ordinances  inconsistent  here- 
with are  hereby  repealed. 

Section  17.  This  ordinance  shall  take  effect  and  be  in  force  from  and 
after  its  passage  and  publication. 

Passed  Dec.  5,  1904.  M.  B.  CUU.UM, 

Approved  Dec.  7,  1904.  Mayor. 

Attest : 

H.  W.  CHEADI.E,  Citv  Clerk. 


APPENDIX   D. 


BLANK  FOR  REPORTING  EXISTENCE  OF  INFECTIOUS 

DISEASES. 


DEPARTMENT  OF  HEAI/TH,  THE  CITY  OF  NEW  YORK. 

Report  of  Dairymen  to  be  Filled  Out  and  Delivered  at  Creamery  Every 
Saturday  Morning. 

Date.... 
To  the  Manager  : 

..Creamery. 
.Town. 
...State. 
Sir: 

In  accordance  with  the  requirements  of  the  Board  of  Health  of  the 
Department  of  Health  of  the  City  of  New  York  in  relation  to  infectious 
disease*  among  milk  handlers,  I  make  the  following1  statement  upon  my 
honor. 

Owner  of  Farm... 
Operator  of  Dairy.... 
Location 

No.  of  Persons  in  Family          No.  of  Persons  in  Households  of 

Farm  Hands..  No.  of  "Summer  Boarders" 

There  are  no  cases  of  infectious  diseases  among  any  of  the  above  men- 
tioned persons,  except  as  hereinafter  stated. 

NAME  OF  PATIENT.  DISEASE.  ATTENDING  PHYSICIAN. 


Respectfully, 


The  following  infectious  diseases  are  to  be  reported  : 

Measles  Varicella  (Chicken  Pox)        Erysipelas 

Rubella  (German  Measles)     Diphtheria  Whoopinyr  Coiitfh 

vScarlet  Fever  Typhoid  Fever          Epidemic  Cerebro-Spinal  Meningitis 

Small  Pox  Tuberculosis  (Consumption) 

(This  report  to  be  kept  on  file  in  creamery  at  least  six  months. ) 


APPENDIX  E. 


POSTER  FOR  DAIRY  BARNS. 
TWENTY  DAIRY  SUGGESTIONS  WITH  SPKCIAI,  RKKKKKNCIV  TO  SANITATION. 


fnited  States  Department  of  Agriculture,  Bureau  of  Ajiimal   Industry, 

Dairy  Division. 

THK  Cows. 

1.  Have  the  herd  examined  at  least  twice  a  year  by  a  skilled   veteri- 

narian. Promptly  remove  animals  suspected  of  being  in  bad  health. 
Never  add  an  animal  to  the  herd  until  certain  it  is  free  from  dis- 
ease, particularly  tuberculosis. 

2.  Never  allow  a  cow  to  be  excited  by  fast  driving,  abuse,  loud  talking. 

or  unnecessary  disturbance  ;  do  not  expose  her  to  cold  or  storms 
more  than  necessary. 

3.  Clean  the   entire  body  of  the  cow  daily  ;    hair  in  the  region  of  the 

udder  should  be  kept  short  by  clipping. 

4.  Do  not  allow  any  strong-flavored  food,  like  garlic,  cabbage,  or  turnips, 

to  be  eaten,  except  immediately  after  milking.  Changes  in  feed 
should  be  made  gradually. 

5.  Provide  fresh  pure  water  in  abundance,  easy  of  access  and  not  too  cold. 

THK  STABILES. 

6.  Dairy  cattle  should  be  kept  in  a  stable,  preferably  without  cellar  or 

storage  loft,  and  where  no  other  animals  are  housed. 

7.  The  stable  should  be  light  (4  square  feet  of  glass  per  cow)  and  dry. 

with  at  least  500  cubic  feet  of  air  space  per  animal.  It  should  have- 
air  inlets  and  outlets,  so  arranged  as  to  give  good  ventilation  with- 
out drafts  of  air  on  cows. 

8.  The  floor  should  be  tight  and   constructed   preferably   of   cement  ; 

walls  and  ceilings  should  be  tight,  clean,  free  from  cobwrebs,  and 
whitewashed  twice  a  year.  Have  as  few  dust-catching  ledges, 
projections,  and  corners  as  possible. 

9.  Allow  no  dusty,  musty,  or  dirty  litter,  or  strong-smelling  material 

in  the  stable.  Haul  manure  to  field  daily,  or  store  under  cover  at 
least  40  feet  from  stable.  Use  land  plaster  daily  in  gutter  and  on 
floor. 


APPENDIX  E.  213 

MII.K  IIorsK. 

10.  Have- a  light,  clean,  well-ventilated,  and  screened  milk  room,  located 

so  as  to  be  free  from  dust  and  odors. 

11.  Milk  utensils  should  be  made  of  metal,  and  all  joints  smoothly  sold- 

ered. Never  allow  utensils  to  become -rusty  or  rough  inside.  Use 
them  only  for  handling,  storing,  or  delivering  milk. 

12.  To  clean  dairy  utensils,  use  only  pure  water.     First  rinse  the  uten- 

sils in  warm  water.  Then  wash  inside  and  out  in  hot  water  in 
which  a  cleansing  material  has  been  dissolved,  and  rinse  again. 
Sterilize  with  boiling  water  or  steam.  Then  keep  inverted  in  pun- 
air  and  sun,  if  possible,  until  wanted  for  use. 

MILKING  AXD  HANDIJNG  MILK. 

13.  Use  no  dry,  dusty  food  just  previous  to  milking. 

14.  The  milker  should  wash  his  hands  immediately  before  milking,  and 

milk  with  dry  hands.  He  should  wear  a  clean  outer  garment, 
kept  in  a  clean  place  when  not  in  use.  Tobacco  should  not  be 
used  while  milking. 

15.  Wipe  the  udder  and  surrounding  parts  with  a  clean  damp  cloth  im- 

mediately before  milking. 

16.  In  milking  be  quiet,  quick,  clean,  and  thorough.      Commence  milk- 

ing at  the  same  hour  every  morning  and  evening,  and  milk  the 
cows  in  the  same  order. 

17.  If  any  part  of  the  milk  is  bloody,  stringy,  or  unnatural  in  appear- 

ance, or  if  by  accident  dirt  gets  into  the  milk  pail,  the  whole  should 
be  rejected. 

18.  Do  not  fill  cans  in  the  stable.     Remove  the  milk  of  each  cow  at  once 

from  the  stable  to  milk  room.  Strain  immediately  through  cotton 
flannel  or  cotton.  Cool  to  50° F.  as  soon  as  strained.  Store  at 
50°  F.  or  lower. 

19.  Never  mix  warm  milk  with  that  which  has  been  cooled,  and  do  not 

allow  milk  to  freeze. 

20.  A  person  suffering  from  any  disease,  or  who  has  been  recently  ex- 

posed to  a  contagions  disease,  must  remain  away  from  the  cows 
and  the  milk. 


INDEX. 


Acid-fast  organisms  ....154 

Acidity  of  milk  ....182 

Tests  for  ....166 

Actinomycosis  .... 86 

Adulteration  of  milk  ..187 

Aeration  of  milk 15,  17,  25 

Amer.  Asso.  Med.  Milk  Com- 
missions  157,  158 

Amer.  Pub.  Health  Asso.. .141,  152 
Ammonia  refrigeration  ....25 

Analysis  of  milk  .174 

Anthrax...  ....86 

Apparatus,  inspection  of 105 

Artificial  digestion  experiments  188 
Aseptic  milking  4,  8,  37 

Ash  of  milk  ....  .176 


B 


Babcock  test  179 

Bacillus  coli  com  munis  27,  55,  152 

Bacillus  diphtheria 52,  115 

Bacillus  lactimorbi  ...  88 

Bacillus  lactis  viscosus      31,  32,  33 

Bacillus  prodigiosus 2,  3 

Bacillus  proteus 55 

Bacillus  pseudo  tuberculosis 154 

Bacillus  subtilis 29 

Bacillus  typhosus,  carriers  of,  45,  49 
Effect  heat  upon ....  ...115 

Examination  of  milk  and 

water  for...... 46,  152 

Germicidal  action  upon         .  36 

In  milk  .45 

Bacteria,  effect  of  temperature 

on  24,34 

Growth  of  .24 

In  foremilk  5 

In  milk  1,  4,  23,  110,  165 

In  udder  .  .1 

Killing  of 115 

Microscopic  determination 

of...  151 

On  udder  3,  4,  6 

Spore-bearing  ..116 

Bactericide  ...  .115,  117 

Bacteriological  examination 

of  milk  .-.141,  165 


Numerical  determinations 

110,  141 

Interpretation  of  results 150 

Bacterium  acidi  lactici  ...27,  28,  133 

Bacterium  diphtheric?,  in  milk...  52 

Effect  heat  upon  ...  .115 

Examination  milk  for  152 

Bacterium  lactis  acidi.          26 

Bacterium  lactis  aerogenes ...  27,  36 
Bacteriu  in  tu  bercu  los  is 

(see  tubercle  bacilli) 

Barns,  improvement  of....  11 

Sanitation  of  ...11 

Barn-yards  ...  5 

Beet  pulp .12 

Benzoic  acid  ....166 

Berkeley,  Cal.,  tuberculin  test 

ordinance...       76,  195 

Typhoid  epidemic  in 49 

Bicarbonate  of  soda 192 

Blended  milk,  Federal  standard  183 

Bloody  milk  .138 

Borax"  ....188,  190 

Test  for  ...166 

Boric  acid ..188,  190 

Boston,  bacteria  in  milk  of 24 

Milk  inspection  in  ....111 

Bottle  cap  ...  ....167 

Sterilization  of  .16 

Varieties  of  .168 

Bottled  milk  .  .16 

Bottles  16,  17 

Bottling  machines .16 

Bovine  tuberculosis 59,  60,  164 

Education  concerning 85 

In  swine  ..60 

Measures  against  ... 67 

Milk-borne 59 

Physical  examination  for 68 

.    Prevalence  of...... ....61 

Views  of  Koch  on    64 

Brewers'  grains 12 

Budde's  method  of  preserving 

milk  .; 26 

Bur.  Anim.  Ind.,  score  card  of 

95,  107 

Buttermilk,  Federal  standard.  .183 


INDEX. 


215 


Carbohydrates  ....176 

Carbon  dioxide  refrigeration 25 

Carbonate  of  soda  192 

Care,  of  cow's  coat 5 

Milking-  machines  9 

Stables..  .  .11 

Udder  6 

Utensils  13,  33 

Casein  in  milk   ....174 

Cells,  tests  for  (see  leucocytes) 

Certified  milk 74,  156 

Amount  produced. ...  .168 

Certification  label 167 

Chemical  examinations       .  166 

Cost  168 

Fraudulent  .  ..168 

Package  ....167 

Sanitary    requirements    of 

dairymen.... 158 

Standards  for 169 

Charbon  (see  anthrax) 

Chemical  examination  of  milk    166 

Chemicals  as  preservatives  .26 

Chicago,  pasteurization  in 121 

Tuberculin  test  ordinance 

76,  200 

City  milk  plants,  score  card 108 

Coat  of  cow.  .  .  5 

Collection  of  samples  ...184 

Coloring  matter  ...193 

Colostrum : 87 

Commercial  pasteurization       ....118 
Commissions,  milk  156 

Experts  of ...164 

Field  of 157 

Source  of  authority 167 

Composition  of  milk  ...  ...  174 

Effect  of  feeding  on 176 

Condensed  milk,  Federal  stand- 
ard  183 

Contamination  of  milk,  1,  2, 6,  45,  62 
Significance ....  ..23 

Continuous-flow  machines  120 

Contracts,  milk 76 

Control  of  milk  supply 93 

Cooked  taste  of  milk 115 

Cooling  milk 15,  25,  37,  121 

Cowpox  ...  87 

Cream,  alteration  by  heat 116 

Thickening  of  ...  193 

Cream,  Federal  standard.... 184 

Cream,  evaporated,  Federal 

standard  ..  ..184 


Dairy  Division,  work  of       102,  169 
Dairymen  and  commissions         158 

Dehorning  86 

Delivery  of  milk  ..16 

Diarrhea,   death  rate 55 

Epidemic 56 

Digestion  experiments 188 

Diphtheria,  milk-borne 51 

Bacilli  (see  Bacterium} 

In  Oroville,  Cal 53 

Swab  examinations 167 

Diseases  of  man  transmitted 

by  milk  41 

Disinfection  of  stables  85 

Dispensaries,   milk  ..  .170 

Distillers'  grains ....12 

District  of  Columbia,   typhoid 

in  42,  47,  123 

Doane- Buckley  test  129 

Duluth,  Minn.,  tuberculin  test 

ordinance 76,  206 

E. 

Education  of  dairymen.  85 

Of  public  ...112 

Epidemic  diarrhea  ....          56 

Epidemic  diseases  and  pasteur- 
ization   • 123 

Epidemic  diseases  transmitted 

by  milk 41,  109 

Evaporated  milk,  Federal 

standard.  183 

Examinations,  bacteriological    .165 
Chemical 166 

Experts  of  milk  commissions  .164 


Fat,  in  certified  milk '174 

And  specific  gravity  180 

Babcock  test  for  179 

Determination  of  179 

Federal  standards 169,  183 

Feeding,  effect  on  composition 

of  milk  ....176 

Feeds  12,  17 

Fermentation,  lactic  acid 26 

Filth  ...  5,  33 

Flavor  of  milk ....  17 

Foot  and  mouth  disease  88 

Foremilk,  bacteria  in..  ....5 

Formaldehyde .    166,  189 

Leach's  test  for 191 

France,  dispensaries  in       170 

Fraudulent  certified  milk             168 
Tuberculin  test ...  80 


216 


INDEX . 


Gastrointestinal  infections  55 

Germicidal  activity  24,  34 

Goat's  milk,  Federal  standard  183 
Croat's  milk  and  Malta  fever         87 


H 


Handling  milk 15 

Heat,  effect  on  cream  116 

Effect  on  milk  36,  115 

Heated  milk,  tests  for  166,  193 

Heating  (see  pasteurization) 
Hehner's  test  for  formaldehyde  191 
High-temperature  pasteuriz- 
ation  118 

Hvdrogen  peroxide  193 

Ily^odcnna  bovis 86 

I 

Identification  of  animals 75,  80 

Indemnification  for  slaughtered 

cows 82 

Infant  feeding  arid  pasteurized 

milk.. 122 

Infant  mortality  ...  55,  171 

Infection,  tuberculous  .65 

Infectious  diseases,    blank  for 

reporting  211 

Inspected  milk  74,  93,  112,  166 

Inspection,  of  city  milk  plants 

.'...   106,  111 

Cows.... 105 

Dairies  93,  123 

Dairy  apparatus  ...  105 

Water  supplies ....106 

Inspectors,  qualifications  of  93 

Intern.  Cong,  on  Tuberculosis  ..66 


Japan,  tuberculosis  in. 
K 


...66 


ivoch,  views  on  tuberculosis 64 


Lactic  acid  fermentation  26 

Leach's  test  for  formaldehyde    191 

Leucocytes  in  milk 36,  134 

Standards  for 127,  131,  137 

Leucocyte  tests     126 

Doane-Buckley  129 

Savage's  ...  131 

Slack's    128 

Stewart's  ...127 


Stokes'.... 126 

Trommsdorff's 131 

Live  stock  industry  .   59 

Low-temperature   pasteuriz- 
ation 117 


M 


Malta  fever 87 

Mammitis  in  cows     69,  86,  126,  136 

Mangers  ... 11 

Manure,  disposal  of 11 

Tubercle  bacilli  in  .  63 

Market  milk,  bacteria  in  ..  24 

Tubercle  bacilli  in 63 

Medical  inspection,  certified 

milk  167 

Micrococci  in  milk 3,  134 

Micrococcus  I  act  is  varians 3 

Micrococcus  melitensis .87 

Micrococcus pyogen/es  aurcus 4 

Microscopic  estimate  of  bacteria  151 
Microscopic  tests  of  milk  ....126 
Milk,  adulteration  of....  187 

Milk-borne  diphtheria     51 

Milk-borne  epidemics     .    .  .41,  109 

Milk-borne  scarlet  fever 54 

Milk  commissions  156 

Experts  of..  164 

Milk,  composition  of    23,  174 

Milk,  contamination  of  1,2,  6,  45,62 

Milk  dispensaries  170 

Milk,  Federal  standard ....         ..183 

•Milk  flavors 17 

Milk,  handling  of 15 

Milk  pail,  shape  of    ..  .7 

Milk  room  12,  16 

Milk  sediments  ....  17 

Milk-sickness  ....88 

Milk,  watering  of  ...191 

Milker  8 

Milking  machines  8 

Mineral  matter 176 

Municipal   sanitary   control    of 

milk"  70,  93 

Of  pasteurization     123 

Of  tuberculin  test  75 

Mvcotic  stomatitis  88 


N 


New  York,  blank  for  infectious 

diseases 121 

Pasteurization  in 121 

N.  Y.  S.  Coll.  of  Agri.,   score 

card  ..97 

Numerical  determinations  (see 

bacteriological  examination) 


INDEX. 


217 


O 


Ordinances,  tuberculin  test     72,  S5 
Berkeley,  Cal.  76,  195 

Chicago,  111.  ...76,  200 

Duluth,  Minn.  76,  206 

Washington,   I).  C.  ...73 


Palo  Alto,  typhoid  epidemic  in     46 

Parturition  disturbances  87 

Pasteurization  of  milk     71,  74,  114 

Commercial  .118 

Continuous-flow  ..  .120 

Efficiency  of...  119 

High-temperature 118 

In  Chicago .  121 

In  New  York  ....121 

In  Washington 73 

Low-temperature    .            ...117 
Machines  for    .                    ..117 
Pasteurized  milk,  Federal  stand- 
ard   183 

For  infant  feeding  ...  122 

Phagocytosis  36 

Physical  examination  for  tuber- 
culosis      ....  ....68 

Preservatives..  .26,  187 

Tests  for... 166,  190 

Protein ..174 

Pus  cells  in  milk  135 

Putrefaction  .  29 


Qualitative  determinations 
R 


154 


Refrigeration  (see  cooling) 

Richmond,  Va.,  score  card  103 

Rochester,  N.  Y.,  milk  dispen-  ' 

saries  ..170 

Rooms,  special  milking  12 

Ropy  milk  30 


St.  I^ouis,  certified  milk  in         167 
Salicylic  acid  166,  188 

Samples,  collection  of  ....184 

Sampling  milk  177 

Sanitary  control  of  barns  ...11 

Of  "milk  93,  158 

Savage's  test  ...  131 

Scalding  of  utensils  13 

Scarlet  fever,  milk-borne  54 

Score  card  .  94,  97,  lo? 


Scores  of  certified  dairies  169 

Scores  of  dairies  in  Richmond, 

Va.  103 

In  Washington,  I).  C.  104 

Sediments  in  milk  17 

Skim  milk,   Federal  standard     183 

Skim  milk,  condensed,  Federal 

standard  .183 

Skimmed  milk,  indication  of      ISO 
Skimming,  tests  for  192 

Slack's  test 128 

Slaughter  of  tubercular  cows        84 
Solids. of  milk  175 

vSolids  not  fat  ISO 

Sour  milk  as  food  28 

Souring  of  milk  26,  29 

Specific  gravity  .  177,180 

Spore-bearing  bacteria  116 

S tables,  dairy  ..10 

Sanitation  of  ...  72 

Stanchions  11 

Standards,  Federal.  ..169,  183 

Standards,  state  .184 

Staphylococctts  pyogencs  aureus 
( see  micrococcus  pyo- 
gciics  nit  re  us] 

State  standards  ...184 

Sterilization  of  milk  114 

Of  utensils  .13 

Sterilized  milk,  Federal  stand- 
ard 183 
Stewart's  test...  127 
Stokes'  test  126 
Strainers ...  15 
Strainer  pails  7 
Straining,  effect  of  8,  17 
Streptococcus  in  gastro-intes- 

tinal  infections          55 

In  mammitis  4,  126 

In  milk 4,  133 

Determination  of  .154 

Streptococcus  I  adieus      26,  27,  133 
Streptococcus  pyogrncs  4 

Strippings ....  2 

Sugar-beet  pulp  12 

Suppuration  86 

Swine,  tuberculosis  in  •          60 


Taints  in  milk  15,  17 

Temperature,  effect  on  bacterial 

'     growth  24,  34 

Interpretation  of  79 

Temperature  standard  of  milk    109 
Temperature  in  tuberculin  test 

...  77,  79 


218 


INDEX. 


Tests,  -Babcock's  179 

Doane-Buckley  '.129 

Hehner's....  191 

Leach's  ...  191 

Microscopic  125 

Municipal  ., 75 

Savage's  131 

Slack's..... 128 

Stewart's ....  127 

Stokes'  .126 

Trommsdorff's  131 

Tuberculin  (see  tuberculin 

test) 
Thickening  agents ....  ....193 

Time  in  pasteurization  ..117 

Toxic  milk ,30 

Toxins 55 

Transportation  of  milk  25 

Trommsdorff' s  test....  131 

Tubercle  bacillus,  bovine  in  man  64 

Effect  of  heat  upon  .115 

In  manure  63 

In  milk  62,  63,  153 

Types  of  63 

Tubercular  animals  84 

Tuberculin  .71,  77,  79 

Tuberculin  test.        .71,  72,  75,  165 

Application  of  77 

Limitations  of  79 

Ordinances  (see ordinances) 

Tuberculosis,  and  milk  supply     67 

Bovine  ...  59 

Channels  of  infection 65 

Disinfection  for 85 

In  Japan  66 

In  swine  60 


International  Congress  on 
Measures  against 
Milk-borne...: 

Of  udder 

Prevalence    

Stable  sanitation 
Tests  for 

Typhoid  fever 

And  pasteurization 

Bacillus 

Epidemics 
Milk -borne.... 


66 

67 

59,  64 


69 
61 

72 
71 
42 

...123 
45,  152 
.46,  49 
42,  123 


U 


Udder,  bacteria  in  1,7 

Cleansing  of  6 

Contamination  from  exterior  6 

Diseases  of  86,  126 

Tuberculosis  of  62,  69 

U.  S.  Dept.  Agri.,  poster  212 

Utensils,  cleansing  of  13 

Construction  of  15 

Inspection  of  .  105 


Veterinary  inspection  164 

Vital  qualities  of  milk  116 

W 

Washington,  control  of  tuber- 
culosis 73 
Milk  supply  24,  73 
Pasteurization  .123 
Score  card  ....104 
Water  supply  of  dairies  106 
Watered  milk,  indication  of  191 


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